Setters/adders now throw ArgumentNullException appropriately.

29 files changed, 597 insertions, 14 deletions

diff --git a/src/AddressBook/AddressBookProtos.cs b/src/AddressBook/AddressBookProtos.cs
index bfe1b48f..4851ae4c 100644
--- a/src/AddressBook/AddressBookProtos.cs
+++ b/src/AddressBook/AddressBookProtos.cs
@@ -286,6 +286,7 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
             set { SetNumber(value); }
           }
           public Builder SetNumber(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasNumber = true;
             result.number_ = value;
             return this;
@@ -553,6 +554,7 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -589,6 +591,7 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
         set { SetEmail(value); }
       }
       public Builder SetEmail(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasEmail = true;
         result.email_ = value;
         return this;
@@ -609,18 +612,22 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
         return result.GetPhone(index);
       }
       public Builder SetPhone(int index, global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.phone_[index] = value;
         return this;
       }
       public Builder SetPhone(int index, global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.phone_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddPhone(global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.phone_.Add(value);
         return this;
       }
       public Builder AddPhone(global::Google.ProtocolBuffers.Examples.AddressBook.Person.Types.PhoneNumber.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.phone_.Add(builderForValue.Build());
         return this;
       }
@@ -825,18 +832,22 @@ namespace Google.ProtocolBuffers.Examples.AddressBook {
         return result.GetPerson(index);
       }
       public Builder SetPerson(int index, global::Google.ProtocolBuffers.Examples.AddressBook.Person value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.person_[index] = value;
         return this;
       }
       public Builder SetPerson(int index, global::Google.ProtocolBuffers.Examples.AddressBook.Person.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.person_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddPerson(global::Google.ProtocolBuffers.Examples.AddressBook.Person value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.person_.Add(value);
         return this;
       }
       public Builder AddPerson(global::Google.ProtocolBuffers.Examples.AddressBook.Person.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.person_.Add(builderForValue.Build());
         return this;
       }
diff --git a/src/ProtoBench/BenchmarkProtoFile.cs b/src/ProtoBench/BenchmarkProtoFile.cs
index d0c7744f..e0a06292 100644
--- a/src/ProtoBench/BenchmarkProtoFile.cs
+++ b/src/ProtoBench/BenchmarkProtoFile.cs
@@ -575,6 +575,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField1(value); }
       }
       public Builder SetField1(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField1 = true;
         result.field1_ = value;
         return this;
@@ -593,6 +594,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField9(value); }
       }
       public Builder SetField9(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField9 = true;
         result.field9_ = value;
         return this;
@@ -611,6 +613,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField18(value); }
       }
       public Builder SetField18(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField18 = true;
         result.field18_ = value;
         return this;
@@ -755,6 +758,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField4(value); }
       }
       public Builder SetField4(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField4 = true;
         result.field4_ = value;
         return this;
@@ -817,6 +821,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField7(value); }
       }
       public Builder SetField7(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField7 = true;
         result.field7_ = value;
         return this;
@@ -997,6 +1002,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField102(value); }
       }
       public Builder SetField102(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField102 = true;
         result.field102_ = value;
         return this;
@@ -1015,6 +1021,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField103(value); }
       }
       public Builder SetField103(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField103 = true;
         result.field103_ = value;
         return this;
@@ -1195,16 +1202,19 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField15(value); }
       }
       public Builder SetField15(global::Google.ProtocolBuffers.ProtoBench.Message2 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField15 = true;
         result.field15_ = value;
         return this;
       }
       public Builder SetField15(global::Google.ProtocolBuffers.ProtoBench.Message2.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasField15 = true;
         result.field15_ = builderForValue.Build();
         return this;
       }
       public Builder MergeField15(global::Google.ProtocolBuffers.ProtoBench.Message2 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasField15 &&
             result.field15_ != global::Google.ProtocolBuffers.ProtoBench.Message2.DefaultInstance) {
             result.field15_ = global::Google.ProtocolBuffers.ProtoBench.Message2.CreateBuilder(result.field15_).MergeFrom(value).BuildPartial();
@@ -1300,6 +1310,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField129(value); }
       }
       public Builder SetField129(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField129 = true;
         result.field129_ = value;
         return this;
@@ -1660,6 +1671,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField15(value); }
       }
       public Builder SetField15(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField15 = true;
         result.field15_ = value;
         return this;
@@ -1912,6 +1924,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField205(value); }
       }
       public Builder SetField205(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField205 = true;
         result.field205_ = value;
         return this;
@@ -2269,6 +2282,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField12(value); }
           }
           public Builder SetField12(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField12 = true;
             result.field12_ = value;
             return this;
@@ -2287,6 +2301,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField13(value); }
           }
           public Builder SetField13(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField13 = true;
             result.field13_ = value;
             return this;
@@ -2307,10 +2322,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
             return result.GetField14(index);
           }
           public Builder SetField14(int index, string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field14_[index] = value;
             return this;
           }
           public Builder AddField14(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field14_.Add(value);
             return this;
           }
@@ -2367,6 +2384,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField27(value); }
           }
           public Builder SetField27(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField27 = true;
             result.field27_ = value;
             return this;
@@ -2403,6 +2421,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField29(value); }
           }
           public Builder SetField29(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField29 = true;
             result.field29_ = value;
             return this;
@@ -2421,6 +2440,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField16(value); }
           }
           public Builder SetField16(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField16 = true;
             result.field16_ = value;
             return this;
@@ -2441,10 +2461,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
             return result.GetField22(index);
           }
           public Builder SetField22(int index, string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field22_[index] = value;
             return this;
           }
           public Builder AddField22(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field22_.Add(value);
             return this;
           }
@@ -2509,6 +2531,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField24(value); }
           }
           public Builder SetField24(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField24 = true;
             result.field24_ = value;
             return this;
@@ -2527,16 +2550,19 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField31(value); }
           }
           public Builder SetField31(global::Google.ProtocolBuffers.ProtoBench.Message4 value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField31 = true;
             result.field31_ = value;
             return this;
           }
           public Builder SetField31(global::Google.ProtocolBuffers.ProtoBench.Message4.Builder builderForValue) {
+            pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
             result.hasField31 = true;
             result.field31_ = builderForValue.Build();
             return this;
           }
           public Builder MergeField31(global::Google.ProtocolBuffers.ProtoBench.Message4 value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             if (result.HasField31 &&
                 result.field31_ != global::Google.ProtocolBuffers.ProtoBench.Message4.DefaultInstance) {
                 result.field31_ = global::Google.ProtocolBuffers.ProtoBench.Message4.CreateBuilder(result.field31_).MergeFrom(value).BuildPartial();
@@ -2913,6 +2939,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField1(value); }
       }
       public Builder SetField1(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField1 = true;
         result.field1_ = value;
         return this;
@@ -3003,6 +3030,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField6(value); }
       }
       public Builder SetField6(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField6 = true;
         result.field6_ = value;
         return this;
@@ -3021,6 +3049,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField2(value); }
       }
       public Builder SetField2(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField2 = true;
         result.field2_ = value;
         return this;
@@ -3311,18 +3340,22 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetGroup1(index);
       }
       public Builder SetGroup1(int index, global::Google.ProtocolBuffers.ProtoBench.Message3.Types.Group1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.group1_[index] = value;
         return this;
       }
       public Builder SetGroup1(int index, global::Google.ProtocolBuffers.ProtoBench.Message3.Types.Group1.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.group1_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddGroup1(global::Google.ProtocolBuffers.ProtoBench.Message3.Types.Group1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.group1_.Add(value);
         return this;
       }
       public Builder AddGroup1(global::Google.ProtocolBuffers.ProtoBench.Message3.Types.Group1.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.group1_.Add(builderForValue.Build());
         return this;
       }
@@ -3345,10 +3378,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetField128(index);
       }
       public Builder SetField128(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field128_[index] = value;
         return this;
       }
       public Builder AddField128(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field128_.Add(value);
         return this;
       }
@@ -3389,10 +3424,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetField127(index);
       }
       public Builder SetField127(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field127_[index] = value;
         return this;
       }
       public Builder AddField127(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field127_.Add(value);
         return this;
       }
diff --git a/src/ProtoBench/BenchmarkSpeedProtoFile.cs b/src/ProtoBench/BenchmarkSpeedProtoFile.cs
index 83b0e8cd..670cccf1 100644
--- a/src/ProtoBench/BenchmarkSpeedProtoFile.cs
+++ b/src/ProtoBench/BenchmarkSpeedProtoFile.cs
@@ -1179,6 +1179,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField1(value); }
       }
       public Builder SetField1(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField1 = true;
         result.field1_ = value;
         return this;
@@ -1197,6 +1198,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField9(value); }
       }
       public Builder SetField9(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField9 = true;
         result.field9_ = value;
         return this;
@@ -1215,6 +1217,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField18(value); }
       }
       public Builder SetField18(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField18 = true;
         result.field18_ = value;
         return this;
@@ -1359,6 +1362,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField4(value); }
       }
       public Builder SetField4(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField4 = true;
         result.field4_ = value;
         return this;
@@ -1421,6 +1425,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField7(value); }
       }
       public Builder SetField7(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField7 = true;
         result.field7_ = value;
         return this;
@@ -1601,6 +1606,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField102(value); }
       }
       public Builder SetField102(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField102 = true;
         result.field102_ = value;
         return this;
@@ -1619,6 +1625,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField103(value); }
       }
       public Builder SetField103(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField103 = true;
         result.field103_ = value;
         return this;
@@ -1799,16 +1806,19 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField15(value); }
       }
       public Builder SetField15(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage2 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField15 = true;
         result.field15_ = value;
         return this;
       }
       public Builder SetField15(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage2.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasField15 = true;
         result.field15_ = builderForValue.Build();
         return this;
       }
       public Builder MergeField15(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage2 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasField15 &&
             result.field15_ != global::Google.ProtocolBuffers.ProtoBench.SpeedMessage2.DefaultInstance) {
             result.field15_ = global::Google.ProtocolBuffers.ProtoBench.SpeedMessage2.CreateBuilder(result.field15_).MergeFrom(value).BuildPartial();
@@ -1904,6 +1914,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField129(value); }
       }
       public Builder SetField129(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField129 = true;
         result.field129_ = value;
         return this;
@@ -2586,6 +2597,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField15(value); }
       }
       public Builder SetField15(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField15 = true;
         result.field15_ = value;
         return this;
@@ -2838,6 +2850,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField205(value); }
       }
       public Builder SetField205(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField205 = true;
         result.field205_ = value;
         return this;
@@ -3472,6 +3485,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField12(value); }
           }
           public Builder SetField12(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField12 = true;
             result.field12_ = value;
             return this;
@@ -3490,6 +3504,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField13(value); }
           }
           public Builder SetField13(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField13 = true;
             result.field13_ = value;
             return this;
@@ -3510,10 +3525,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
             return result.GetField14(index);
           }
           public Builder SetField14(int index, string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field14_[index] = value;
             return this;
           }
           public Builder AddField14(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field14_.Add(value);
             return this;
           }
@@ -3570,6 +3587,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField27(value); }
           }
           public Builder SetField27(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField27 = true;
             result.field27_ = value;
             return this;
@@ -3606,6 +3624,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField29(value); }
           }
           public Builder SetField29(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField29 = true;
             result.field29_ = value;
             return this;
@@ -3624,6 +3643,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField16(value); }
           }
           public Builder SetField16(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField16 = true;
             result.field16_ = value;
             return this;
@@ -3644,10 +3664,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
             return result.GetField22(index);
           }
           public Builder SetField22(int index, string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field22_[index] = value;
             return this;
           }
           public Builder AddField22(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.field22_.Add(value);
             return this;
           }
@@ -3712,6 +3734,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField24(value); }
           }
           public Builder SetField24(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField24 = true;
             result.field24_ = value;
             return this;
@@ -3730,16 +3753,19 @@ namespace Google.ProtocolBuffers.ProtoBench {
             set { SetField31(value); }
           }
           public Builder SetField31(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage4 value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasField31 = true;
             result.field31_ = value;
             return this;
           }
           public Builder SetField31(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage4.Builder builderForValue) {
+            pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
             result.hasField31 = true;
             result.field31_ = builderForValue.Build();
             return this;
           }
           public Builder MergeField31(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage4 value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             if (result.HasField31 &&
                 result.field31_ != global::Google.ProtocolBuffers.ProtoBench.SpeedMessage4.DefaultInstance) {
                 result.field31_ = global::Google.ProtocolBuffers.ProtoBench.SpeedMessage4.CreateBuilder(result.field31_).MergeFrom(value).BuildPartial();
@@ -4570,6 +4596,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField1(value); }
       }
       public Builder SetField1(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField1 = true;
         result.field1_ = value;
         return this;
@@ -4660,6 +4687,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField6(value); }
       }
       public Builder SetField6(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField6 = true;
         result.field6_ = value;
         return this;
@@ -4678,6 +4706,7 @@ namespace Google.ProtocolBuffers.ProtoBench {
         set { SetField2(value); }
       }
       public Builder SetField2(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField2 = true;
         result.field2_ = value;
         return this;
@@ -4968,18 +4997,22 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetGroup1(index);
       }
       public Builder SetGroup1(int index, global::Google.ProtocolBuffers.ProtoBench.SpeedMessage3.Types.Group1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.group1_[index] = value;
         return this;
       }
       public Builder SetGroup1(int index, global::Google.ProtocolBuffers.ProtoBench.SpeedMessage3.Types.Group1.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.group1_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddGroup1(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage3.Types.Group1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.group1_.Add(value);
         return this;
       }
       public Builder AddGroup1(global::Google.ProtocolBuffers.ProtoBench.SpeedMessage3.Types.Group1.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.group1_.Add(builderForValue.Build());
         return this;
       }
@@ -5002,10 +5035,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetField128(index);
       }
       public Builder SetField128(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field128_[index] = value;
         return this;
       }
       public Builder AddField128(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field128_.Add(value);
         return this;
       }
@@ -5046,10 +5081,12 @@ namespace Google.ProtocolBuffers.ProtoBench {
         return result.GetField127(index);
       }
       public Builder SetField127(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field127_[index] = value;
         return this;
       }
       public Builder AddField127(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field127_.Add(value);
         return this;
       }
diff --git a/src/ProtoGen/FieldGeneratorBase.cs b/src/ProtoGen/FieldGeneratorBase.cs
index f59da644..207f3fdc 100644
--- a/src/ProtoGen/FieldGeneratorBase.cs
+++ b/src/ProtoGen/FieldGeneratorBase.cs
@@ -1,6 +1,6 @@
 using System;
-using Google.ProtocolBuffers.Descriptors;
 using System.Globalization;
+using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers.ProtoGen {
   internal abstract class FieldGeneratorBase : SourceGeneratorBase<FieldDescriptor> {
@@ -87,6 +87,45 @@ namespace Google.ProtocolBuffers.ProtoGen {
       get { return Descriptor.FieldNumber; }
     }
 
+    protected void AddNullCheck(TextGenerator writer) {
+      AddNullCheck(writer, "value");
+    }
+
+    protected void AddNullCheck(TextGenerator writer, string name) {
+      if (IsNullableType) {
+        writer.WriteLine("  pb::ThrowHelper.ThrowIfNull({0}, \"{0}\");", name);
+      }
+    }
+
+    protected bool IsNullableType {
+      get {
+        switch (Descriptor.FieldType) {
+          case FieldType.Float:
+          case FieldType.Double:
+          case FieldType.Int32:
+          case FieldType.Int64:
+          case FieldType.SInt32:
+          case FieldType.SInt64:
+          case FieldType.SFixed32:
+          case FieldType.SFixed64:
+          case FieldType.UInt32:
+          case FieldType.UInt64:
+          case FieldType.Fixed32:
+          case FieldType.Fixed64:
+          case FieldType.Bool:
+          case FieldType.Enum:
+            return false;
+          case FieldType.Bytes:
+          case FieldType.String:
+          case FieldType.Message:
+          case FieldType.Group:
+            return true;
+          default:
+            throw new InvalidOperationException("Invalid field descriptor type");
+        }
+      }
+    }
+
     protected string TypeName {
       get {
         switch (Descriptor.FieldType) {
diff --git a/src/ProtoGen/MessageFieldGenerator.cs b/src/ProtoGen/MessageFieldGenerator.cs
index 7b5b66e8..55bb7727 100644
--- a/src/ProtoGen/MessageFieldGenerator.cs
+++ b/src/ProtoGen/MessageFieldGenerator.cs
@@ -27,16 +27,19 @@ namespace Google.ProtocolBuffers.ProtoGen {
       writer.WriteLine("  set {{ Set{0}(value); }}", PropertyName);
       writer.WriteLine("}");
       writer.WriteLine("public Builder Set{0}({1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.has{0} = true;", PropertyName);
       writer.WriteLine("  result.{0}_ = value;", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       writer.WriteLine("public Builder Set{0}({1}.Builder builderForValue) {{", PropertyName, TypeName);
+      AddNullCheck(writer, "builderForValue");
       writer.WriteLine("  result.has{0} = true;", PropertyName);
       writer.WriteLine("  result.{0}_ = builderForValue.Build();", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       writer.WriteLine("public Builder Merge{0}({1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  if (result.Has{0} &&", PropertyName);
       writer.WriteLine("      result.{0}_ != {1}) {{", Name, DefaultValue);
       writer.WriteLine("      result.{0}_ = {1}.CreateBuilder(result.{0}_).MergeFrom(value).BuildPartial();", Name, TypeName);
diff --git a/src/ProtoGen/PrimitiveFieldGenerator.cs b/src/ProtoGen/PrimitiveFieldGenerator.cs
index dc733c0b..3c2fb246 100644
--- a/src/ProtoGen/PrimitiveFieldGenerator.cs
+++ b/src/ProtoGen/PrimitiveFieldGenerator.cs
@@ -29,6 +29,7 @@ namespace Google.ProtocolBuffers.ProtoGen {
       writer.WriteLine("  set {{ Set{0}(value); }}", PropertyName);
       writer.WriteLine("}");
       writer.WriteLine("public Builder Set{0}({1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.has{0} = true;", PropertyName);
       writer.WriteLine("  result.{0}_ = value;", Name);
       writer.WriteLine("  return this;");
diff --git a/src/ProtoGen/RepeatedMessageFieldGenerator.cs b/src/ProtoGen/RepeatedMessageFieldGenerator.cs
index c7741ae5..6a9f8e99 100644
--- a/src/ProtoGen/RepeatedMessageFieldGenerator.cs
+++ b/src/ProtoGen/RepeatedMessageFieldGenerator.cs
@@ -38,20 +38,24 @@ namespace Google.ProtocolBuffers.ProtoGen {
       writer.WriteLine("  return result.Get{0}(index);", PropertyName);
       writer.WriteLine("}");
       writer.WriteLine("public Builder Set{0}(int index, {1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.{0}_[index] = value;", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       // Extra overload for builder (just on messages)
       writer.WriteLine("public Builder Set{0}(int index, {1}.Builder builderForValue) {{", PropertyName, TypeName);
+      AddNullCheck(writer, "builderForValue");
       writer.WriteLine("  result.{0}_[index] = builderForValue.Build();", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       writer.WriteLine("public Builder Add{0}({1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.{0}_.Add(value);", Name, TypeName);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       // Extra overload for builder (just on messages)
       writer.WriteLine("public Builder Add{0}({1}.Builder builderForValue) {{", PropertyName, TypeName);
+      AddNullCheck(writer, "builderForValue");
       writer.WriteLine("  result.{0}_.Add(builderForValue.Build());", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
diff --git a/src/ProtoGen/RepeatedPrimitiveFieldGenerator.cs b/src/ProtoGen/RepeatedPrimitiveFieldGenerator.cs
index 4e079dc3..3650642f 100644
--- a/src/ProtoGen/RepeatedPrimitiveFieldGenerator.cs
+++ b/src/ProtoGen/RepeatedPrimitiveFieldGenerator.cs
@@ -38,10 +38,12 @@ namespace Google.ProtocolBuffers.ProtoGen {
       writer.WriteLine("  return result.Get{0}(index);", PropertyName);
       writer.WriteLine("}");
       writer.WriteLine("public Builder Set{0}(int index, {1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.{0}_[index] = value;", Name);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
       writer.WriteLine("public Builder Add{0}({1} value) {{", PropertyName, TypeName);
+      AddNullCheck(writer);
       writer.WriteLine("  result.{0}_.Add(value);", Name, TypeName);
       writer.WriteLine("  return this;");
       writer.WriteLine("}");
diff --git a/src/ProtocolBuffers.Test/DynamicMessageTest.cs b/src/ProtocolBuffers.Test/DynamicMessageTest.cs
index 7179da5d..045f5c4f 100644
--- a/src/ProtocolBuffers.Test/DynamicMessageTest.cs
+++ b/src/ProtocolBuffers.Test/DynamicMessageTest.cs
@@ -54,15 +54,27 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void DynamicMessageSettersRejectNull() {
+      IBuilder builder = DynamicMessage.CreateBuilder(TestAllTypes.Descriptor);
+      reflectionTester.AssertReflectionSettersRejectNull(builder);
+	  }
+
+    [Test]
     public void DynamicMessageExtensionAccessors() {
-    // We don't need to extensively test DynamicMessage's handling of
-    // extensions because, frankly, it doesn't do anything special with them.
-    // It treats them just like any other fields.
-    IBuilder builder = DynamicMessage.CreateBuilder(TestAllExtensions.Descriptor);
-    extensionsReflectionTester.SetAllFieldsViaReflection(builder);
-    IMessage message = builder.WeakBuild();
-    extensionsReflectionTester.AssertAllFieldsSetViaReflection(message);
-  }
+      // We don't need to extensively test DynamicMessage's handling of
+      // extensions because, frankly, it doesn't do anything special with them.
+      // It treats them just like any other fields.
+      IBuilder builder = DynamicMessage.CreateBuilder(TestAllExtensions.Descriptor);
+      extensionsReflectionTester.SetAllFieldsViaReflection(builder);
+      IMessage message = builder.WeakBuild();
+      extensionsReflectionTester.AssertAllFieldsSetViaReflection(message);
+    }
+
+    [Test]
+    public void DynamicMessageExtensionSettersRejectNull() {
+      IBuilder builder = DynamicMessage.CreateBuilder(TestAllExtensions.Descriptor);
+      extensionsReflectionTester.AssertReflectionSettersRejectNull(builder);
+	  }
 
     [Test]
     public void DynamicMessageRepeatedSetters() {
@@ -74,6 +86,12 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void DynamicMessageRepeatedSettersRejectNull() {
+      IBuilder builder = DynamicMessage.CreateBuilder(TestAllTypes.Descriptor);
+      reflectionTester.AssertReflectionRepeatedSettersRejectNull(builder);
+    }
+
+    [Test]
     public void DynamicMessageDefaults() {
       reflectionTester.AssertClearViaReflection(DynamicMessage.GetDefaultInstance(TestAllTypes.Descriptor));
       reflectionTester.AssertClearViaReflection(DynamicMessage.CreateBuilder(TestAllTypes.Descriptor).Build());
diff --git a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
index d97b0ed5..5d0a9291 100644
--- a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
+++ b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
@@ -103,7 +103,20 @@ namespace Google.ProtocolBuffers {
       TestAllTypes message = builder.Build();
       TestUtil.AssertAllFieldsSet(message);
     }
-    
+
+    [Test]
+    public void SettersRejectNull() {
+      TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
+      TestUtil.AssertArgumentNullException(() => builder.SetOptionalString(null));
+      TestUtil.AssertArgumentNullException(() => builder.SetOptionalBytes(null));
+      TestUtil.AssertArgumentNullException(() => builder.SetOptionalNestedMessage((TestAllTypes.Types.NestedMessage)null));
+      TestUtil.AssertArgumentNullException(() => builder.SetOptionalNestedMessage((TestAllTypes.Types.NestedMessage.Builder)null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRepeatedString(null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRepeatedBytes(null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRepeatedNestedMessage((TestAllTypes.Types.NestedMessage)null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRepeatedNestedMessage((TestAllTypes.Types.NestedMessage.Builder)null));
+    }
+
     [Test]
     public void RepeatedSetters() {
       TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
@@ -131,6 +144,18 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void RepeatedAppendRejectsNull() {
+      TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
+
+      ForeignMessage foreignMessage = ForeignMessage.CreateBuilder().SetC(12).Build();
+      TestUtil.AssertArgumentNullException(() => builder.AddRangeRepeatedForeignMessage(new[] { foreignMessage, null }));
+      TestUtil.AssertArgumentNullException(() => builder.AddRangeRepeatedForeignMessage(null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRangeRepeatedForeignEnum(null));
+      TestUtil.AssertArgumentNullException(() => builder.AddRangeRepeatedString(new[] { "one", null }));
+      TestUtil.AssertArgumentNullException(() => builder.AddRangeRepeatedBytes(new[] { TestUtil.ToBytes("one"), null }));
+    }
+
+    [Test]
     public void SettingForeignMessageUsingBuilder() {
       TestAllTypes message = TestAllTypes.CreateBuilder()
           // Pass builder for foreign message instance.
@@ -182,6 +207,11 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void ReflectionSettersRejectNull() {
+      TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
+      reflectionTester.AssertReflectionSettersRejectNull(builder);
+    }
+    [Test]
     public void ReflectionRepeatedSetters() {
       TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
       reflectionTester.SetAllFieldsViaReflection(builder);
@@ -191,6 +221,12 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void TestReflectionRepeatedSettersRejectNull() {
+      TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
+      reflectionTester.AssertReflectionRepeatedSettersRejectNull(builder);
+    }
+
+    [Test]
     public void ReflectionDefaults() {
       reflectionTester.AssertClearViaReflection(TestAllTypes.DefaultInstance);
       reflectionTester.AssertClearViaReflection(TestAllTypes.CreateBuilder().Build());
@@ -238,6 +274,12 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void ExtensionReflectionSettersRejectNull() {
+      TestAllExtensions.Builder builder = TestAllExtensions.CreateBuilder();
+      extensionsReflectionTester.AssertReflectionSettersRejectNull(builder);
+    }
+
+    [Test]
     public void ExtensionReflectionRepeatedSetters() {
       TestAllExtensions.Builder builder = TestAllExtensions.CreateBuilder();
       extensionsReflectionTester.SetAllFieldsViaReflection(builder);
@@ -247,6 +289,12 @@ namespace Google.ProtocolBuffers {
     }
 
     [Test]
+    public void ExtensionReflectionRepeatedSettersRejectNull() {
+      TestAllExtensions.Builder builder = TestAllExtensions.CreateBuilder();
+      extensionsReflectionTester.AssertReflectionRepeatedSettersRejectNull(builder);
+    }
+
+    [Test]
     public void ExtensionReflectionDefaults() {
       extensionsReflectionTester.AssertClearViaReflection(TestAllExtensions.DefaultInstance);
       extensionsReflectionTester.AssertClearViaReflection(TestAllExtensions.CreateBuilder().Build());
@@ -265,6 +313,18 @@ namespace Google.ProtocolBuffers {
           .GetExtensionCount(UnitTestProtoFile.RepeatedInt32Extension));
     }
 
+    /* Reinstate this test in the commit where it's fixed...
+    [Test]
+    public void ExtensionMergeFrom() {
+      TestAllExtensions original = TestAllExtensions.CreateBuilder()
+          .SetExtension(UnitTestProtoFile.OptionalInt32Extension, 1).Build();
+      TestAllExtensions merged =
+          TestAllExtensions.CreateBuilder().MergeFrom(original).Build();
+      Assert.IsTrue((merged.HasExtension(UnitTestProtoFile.OptionalInt32Extension)));
+      Assert.AreEqual(1, (int)merged.GetExtension(UnitTestProtoFile.OptionalInt32Extension));
+    }
+    */
+
     /* Removed multiple files option for the moment
     [Test]
     public void MultipleFilesOption() {
diff --git a/src/ProtocolBuffers.Test/ReflectionTester.cs b/src/ProtocolBuffers.Test/ReflectionTester.cs
index 889b2f6b..767c8cc9 100644
--- a/src/ProtocolBuffers.Test/ReflectionTester.cs
+++ b/src/ProtocolBuffers.Test/ReflectionTester.cs
@@ -810,5 +810,37 @@ namespace Google.ProtocolBuffers {
       Assert.AreEqual("524", message[f("repeated_string_piece"), 1]);
       Assert.AreEqual("525", message[f("repeated_cord"), 1]);
     }
+
+    /// <summary>
+    /// Verifies that the reflection setters for the given Builder object throw an
+    /// ArgumentNullException if they are passed a null value. 
+    /// </summary>
+    public void AssertReflectionSettersRejectNull(IBuilder builder) {
+      TestUtil.AssertArgumentNullException(() => builder[f("optional_string")] = null);
+      TestUtil.AssertArgumentNullException(() => builder[f("optional_bytes")] = null);
+      TestUtil.AssertArgumentNullException(() => builder[f("optional_nested_enum")] = null);
+      TestUtil.AssertArgumentNullException(() => builder[f("optional_nested_message")] = null);
+      TestUtil.AssertArgumentNullException(() => builder[f("optional_nested_message")] = null);
+      TestUtil.AssertArgumentNullException(() => builder.WeakAddRepeatedField(f("repeated_string"), null));
+      TestUtil.AssertArgumentNullException(() => builder.WeakAddRepeatedField(f("repeated_bytes"), null));
+      TestUtil.AssertArgumentNullException(() => builder.WeakAddRepeatedField(f("repeated_nested_enum"), null));
+      TestUtil.AssertArgumentNullException(() => builder.WeakAddRepeatedField(f("repeated_nested_message"), null));
+    }
+
+    /// <summary>
+    /// Verifies that the reflection repeated setters for the given Builder object throw an
+    /// ArgumentNullException if they are passed a null value.
+    /// </summary>
+    public void AssertReflectionRepeatedSettersRejectNull(IBuilder builder) {
+      builder.WeakAddRepeatedField(f("repeated_string"), "one");
+      TestUtil.AssertArgumentNullException(() => builder.SetRepeatedField(f("repeated_string"), 0, null));
+      builder.WeakAddRepeatedField(f("repeated_bytes"), TestUtil.ToBytes("one"));
+      TestUtil.AssertArgumentNullException(() => builder.SetRepeatedField(f("repeated_bytes"), 0, null));
+      builder.WeakAddRepeatedField(f("repeated_nested_enum"), nestedBaz);
+      TestUtil.AssertArgumentNullException(() => builder.SetRepeatedField(f("repeated_nested_enum"), 0, null));
+      builder.WeakAddRepeatedField(f("repeated_nested_message"),
+          new TestAllTypes.Types.NestedMessage.Builder { Bb = 218 }.Build());
+      TestUtil.AssertArgumentNullException(() => builder.SetRepeatedField(f("repeated_nested_message"), 0, null));
+    }
   }
 }
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
index ff777cbb..df8d7998 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestCustomOptionsProtoFile.cs
@@ -397,6 +397,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetField1(value); }
       }
       public Builder SetField1(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasField1 = true;
         result.field1_ = value;
         return this;
@@ -1593,16 +1594,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetBar(value); }
       }
       public Builder SetBar(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasBar = true;
         result.bar_ = value;
         return this;
       }
       public Builder SetBar(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType1.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasBar = true;
         result.bar_ = builderForValue.Build();
         return this;
       }
       public Builder MergeBar(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType1 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasBar &&
             result.bar_ != global::Google.ProtocolBuffers.TestProtos.ComplexOptionType1.DefaultInstance) {
             result.bar_ = global::Google.ProtocolBuffers.TestProtos.ComplexOptionType1.CreateBuilder(result.bar_).MergeFrom(value).BuildPartial();
@@ -1644,16 +1648,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetFred(value); }
       }
       public Builder SetFred(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType2.Types.ComplexOptionType4 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasFred = true;
         result.fred_ = value;
         return this;
       }
       public Builder SetFred(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType2.Types.ComplexOptionType4.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasFred = true;
         result.fred_ = builderForValue.Build();
         return this;
       }
       public Builder MergeFred(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType2.Types.ComplexOptionType4 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasFred &&
             result.fred_ != global::Google.ProtocolBuffers.TestProtos.ComplexOptionType2.Types.ComplexOptionType4.DefaultInstance) {
             result.fred_ = global::Google.ProtocolBuffers.TestProtos.ComplexOptionType2.Types.ComplexOptionType4.CreateBuilder(result.fred_).MergeFrom(value).BuildPartial();
@@ -1925,16 +1932,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetComplexOptionType5(value); }
       }
       public Builder SetComplexOptionType5(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType3.Types.ComplexOptionType5 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasComplexOptionType5 = true;
         result.complexOptionType5_ = value;
         return this;
       }
       public Builder SetComplexOptionType5(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType3.Types.ComplexOptionType5.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasComplexOptionType5 = true;
         result.complexOptionType5_ = builderForValue.Build();
         return this;
       }
       public Builder MergeComplexOptionType5(global::Google.ProtocolBuffers.TestProtos.ComplexOptionType3.Types.ComplexOptionType5 value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasComplexOptionType5 &&
             result.complexOptionType5_ != global::Google.ProtocolBuffers.TestProtos.ComplexOptionType3.Types.ComplexOptionType5.DefaultInstance) {
             result.complexOptionType5_ = global::Google.ProtocolBuffers.TestProtos.ComplexOptionType3.Types.ComplexOptionType5.CreateBuilder(result.complexOptionType5_).MergeFrom(value).BuildPartial();
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs
index 1f3a3d40..5af7fd8e 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestEmbedOptimizeForProtoFile.cs
@@ -256,16 +256,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalMessage(value); }
       }
       public Builder SetOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalMessage = true;
         result.optionalMessage_ = value;
         return this;
       }
       public Builder SetOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalMessage = true;
         result.optionalMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalMessage &&
             result.optionalMessage_ != global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize.DefaultInstance) {
             result.optionalMessage_ = global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize.CreateBuilder(result.optionalMessage_).MergeFrom(value).BuildPartial();
@@ -291,18 +294,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedMessage(index);
       }
       public Builder SetRepeatedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessage_[index] = value;
         return this;
       }
       public Builder SetRepeatedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessage_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedMessage(global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessage_.Add(value);
         return this;
       }
       public Builder AddRepeatedMessage(global::Google.ProtocolBuffers.TestProtos.TestOptimizedForSize.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessage_.Add(builderForValue.Build());
         return this;
       }
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
index 557a029b..796d74a8 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestMessageSetProtoFile.cs
@@ -410,16 +410,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetMessageSet(value); }
       }
       public Builder SetMessageSet(global::Google.ProtocolBuffers.TestProtos.TestMessageSet value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasMessageSet = true;
         result.messageSet_ = value;
         return this;
       }
       public Builder SetMessageSet(global::Google.ProtocolBuffers.TestProtos.TestMessageSet.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasMessageSet = true;
         result.messageSet_ = builderForValue.Build();
         return this;
       }
       public Builder MergeMessageSet(global::Google.ProtocolBuffers.TestProtos.TestMessageSet value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasMessageSet &&
             result.messageSet_ != global::Google.ProtocolBuffers.TestProtos.TestMessageSet.DefaultInstance) {
             result.messageSet_ = global::Google.ProtocolBuffers.TestProtos.TestMessageSet.CreateBuilder(result.messageSet_).MergeFrom(value).BuildPartial();
@@ -813,6 +816,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetStr(value); }
       }
       public Builder SetStr(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasStr = true;
         result.str_ = value;
         return this;
@@ -1071,6 +1075,7 @@ namespace Google.ProtocolBuffers.TestProtos {
             set { SetMessage(value); }
           }
           public Builder SetMessage(pb::ByteString value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasMessage = true;
             result.message_ = value;
             return this;
@@ -1251,18 +1256,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetItem(index);
       }
       public Builder SetItem(int index, global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.item_[index] = value;
         return this;
       }
       public Builder SetItem(int index, global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.item_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddItem(global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.item_.Add(value);
         return this;
       }
       public Builder AddItem(global::Google.ProtocolBuffers.TestProtos.RawMessageSet.Types.Item.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.item_.Add(builderForValue.Build());
         return this;
       }
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs
index 65ed149a..777a4c23 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestOptimizeForProtoFile.cs
@@ -189,16 +189,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetMsg(value); }
       }
       public Builder SetMsg(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasMsg = true;
         result.msg_ = value;
         return this;
       }
       public Builder SetMsg(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasMsg = true;
         result.msg_ = builderForValue.Build();
         return this;
       }
       public Builder MergeMsg(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasMsg &&
             result.msg_ != global::Google.ProtocolBuffers.TestProtos.ForeignMessage.DefaultInstance) {
             result.msg_ = global::Google.ProtocolBuffers.TestProtos.ForeignMessage.CreateBuilder(result.msg_).MergeFrom(value).BuildPartial();
@@ -438,16 +441,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetO(value); }
       }
       public Builder SetO(global::Google.ProtocolBuffers.TestProtos.TestRequiredOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasO = true;
         result.o_ = value;
         return this;
       }
       public Builder SetO(global::Google.ProtocolBuffers.TestProtos.TestRequiredOptimizedForSize.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasO = true;
         result.o_ = builderForValue.Build();
         return this;
       }
       public Builder MergeO(global::Google.ProtocolBuffers.TestProtos.TestRequiredOptimizedForSize value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasO &&
             result.o_ != global::Google.ProtocolBuffers.TestProtos.TestRequiredOptimizedForSize.DefaultInstance) {
             result.o_ = global::Google.ProtocolBuffers.TestProtos.TestRequiredOptimizedForSize.CreateBuilder(result.o_).MergeFrom(value).BuildPartial();
diff --git a/src/ProtocolBuffers.Test/TestProtos/UnitTestProtoFile.cs b/src/ProtocolBuffers.Test/TestProtos/UnitTestProtoFile.cs
index bc648d12..17501997 100644
--- a/src/ProtocolBuffers.Test/TestProtos/UnitTestProtoFile.cs
+++ b/src/ProtocolBuffers.Test/TestProtos/UnitTestProtoFile.cs
@@ -3255,6 +3255,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalString(value); }
       }
       public Builder SetOptionalString(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalString = true;
         result.optionalString_ = value;
         return this;
@@ -3273,6 +3274,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalBytes(value); }
       }
       public Builder SetOptionalBytes(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalBytes = true;
         result.optionalBytes_ = value;
         return this;
@@ -3291,16 +3293,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalGroup(value); }
       }
       public Builder SetOptionalGroup(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.OptionalGroup value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalGroup = true;
         result.optionalGroup_ = value;
         return this;
       }
       public Builder SetOptionalGroup(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.OptionalGroup.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalGroup = true;
         result.optionalGroup_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalGroup(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.OptionalGroup value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalGroup &&
             result.optionalGroup_ != global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.OptionalGroup.DefaultInstance) {
             result.optionalGroup_ = global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.OptionalGroup.CreateBuilder(result.optionalGroup_).MergeFrom(value).BuildPartial();
@@ -3324,16 +3329,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalNestedMessage(value); }
       }
       public Builder SetOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalNestedMessage = true;
         result.optionalNestedMessage_ = value;
         return this;
       }
       public Builder SetOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalNestedMessage = true;
         result.optionalNestedMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalNestedMessage &&
             result.optionalNestedMessage_ != global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.DefaultInstance) {
             result.optionalNestedMessage_ = global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.CreateBuilder(result.optionalNestedMessage_).MergeFrom(value).BuildPartial();
@@ -3357,16 +3365,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalForeignMessage(value); }
       }
       public Builder SetOptionalForeignMessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalForeignMessage = true;
         result.optionalForeignMessage_ = value;
         return this;
       }
       public Builder SetOptionalForeignMessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalForeignMessage = true;
         result.optionalForeignMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalForeignMessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalForeignMessage &&
             result.optionalForeignMessage_ != global::Google.ProtocolBuffers.TestProtos.ForeignMessage.DefaultInstance) {
             result.optionalForeignMessage_ = global::Google.ProtocolBuffers.TestProtos.ForeignMessage.CreateBuilder(result.optionalForeignMessage_).MergeFrom(value).BuildPartial();
@@ -3390,16 +3401,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalImportMessage(value); }
       }
       public Builder SetOptionalImportMessage(global::Google.ProtocolBuffers.TestProtos.ImportMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalImportMessage = true;
         result.optionalImportMessage_ = value;
         return this;
       }
       public Builder SetOptionalImportMessage(global::Google.ProtocolBuffers.TestProtos.ImportMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalImportMessage = true;
         result.optionalImportMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalImportMessage(global::Google.ProtocolBuffers.TestProtos.ImportMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalImportMessage &&
             result.optionalImportMessage_ != global::Google.ProtocolBuffers.TestProtos.ImportMessage.DefaultInstance) {
             result.optionalImportMessage_ = global::Google.ProtocolBuffers.TestProtos.ImportMessage.CreateBuilder(result.optionalImportMessage_).MergeFrom(value).BuildPartial();
@@ -3477,6 +3491,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalStringPiece(value); }
       }
       public Builder SetOptionalStringPiece(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalStringPiece = true;
         result.optionalStringPiece_ = value;
         return this;
@@ -3495,6 +3510,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalCord(value); }
       }
       public Builder SetOptionalCord(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalCord = true;
         result.optionalCord_ = value;
         return this;
@@ -3853,10 +3869,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedString(index);
       }
       public Builder SetRepeatedString(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedString_[index] = value;
         return this;
       }
       public Builder AddRepeatedString(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedString_.Add(value);
         return this;
       }
@@ -3879,10 +3897,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedBytes(index);
       }
       public Builder SetRepeatedBytes(int index, pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedBytes_[index] = value;
         return this;
       }
       public Builder AddRepeatedBytes(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedBytes_.Add(value);
         return this;
       }
@@ -3905,18 +3925,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedGroup(index);
       }
       public Builder SetRepeatedGroup(int index, global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.RepeatedGroup value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedGroup_[index] = value;
         return this;
       }
       public Builder SetRepeatedGroup(int index, global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.RepeatedGroup.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedGroup_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedGroup(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.RepeatedGroup value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedGroup_.Add(value);
         return this;
       }
       public Builder AddRepeatedGroup(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.RepeatedGroup.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedGroup_.Add(builderForValue.Build());
         return this;
       }
@@ -3939,18 +3963,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedNestedMessage(index);
       }
       public Builder SetRepeatedNestedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedNestedMessage_[index] = value;
         return this;
       }
       public Builder SetRepeatedNestedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedNestedMessage_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedNestedMessage_.Add(value);
         return this;
       }
       public Builder AddRepeatedNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedNestedMessage_.Add(builderForValue.Build());
         return this;
       }
@@ -3973,18 +4001,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedForeignMessage(index);
       }
       public Builder SetRepeatedForeignMessage(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedForeignMessage_[index] = value;
         return this;
       }
       public Builder SetRepeatedForeignMessage(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedForeignMessage_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedForeignMessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedForeignMessage_.Add(value);
         return this;
       }
       public Builder AddRepeatedForeignMessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedForeignMessage_.Add(builderForValue.Build());
         return this;
       }
@@ -4007,18 +4039,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedImportMessage(index);
       }
       public Builder SetRepeatedImportMessage(int index, global::Google.ProtocolBuffers.TestProtos.ImportMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedImportMessage_[index] = value;
         return this;
       }
       public Builder SetRepeatedImportMessage(int index, global::Google.ProtocolBuffers.TestProtos.ImportMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedImportMessage_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedImportMessage(global::Google.ProtocolBuffers.TestProtos.ImportMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedImportMessage_.Add(value);
         return this;
       }
       public Builder AddRepeatedImportMessage(global::Google.ProtocolBuffers.TestProtos.ImportMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedImportMessage_.Add(builderForValue.Build());
         return this;
       }
@@ -4119,10 +4155,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedStringPiece(index);
       }
       public Builder SetRepeatedStringPiece(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringPiece_[index] = value;
         return this;
       }
       public Builder AddRepeatedStringPiece(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringPiece_.Add(value);
         return this;
       }
@@ -4145,10 +4183,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedCord(index);
       }
       public Builder SetRepeatedCord(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedCord_[index] = value;
         return this;
       }
       public Builder AddRepeatedCord(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedCord_.Add(value);
         return this;
       }
@@ -4403,6 +4443,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetDefaultString(value); }
       }
       public Builder SetDefaultString(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasDefaultString = true;
         result.defaultString_ = value;
         return this;
@@ -4421,6 +4462,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetDefaultBytes(value); }
       }
       public Builder SetDefaultBytes(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasDefaultBytes = true;
         result.defaultBytes_ = value;
         return this;
@@ -4493,6 +4535,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetDefaultStringPiece(value); }
       }
       public Builder SetDefaultStringPiece(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasDefaultStringPiece = true;
         result.defaultStringPiece_ = value;
         return this;
@@ -4511,6 +4554,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetDefaultCord(value); }
       }
       public Builder SetDefaultCord(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasDefaultCord = true;
         result.defaultCord_ = value;
         return this;
@@ -6975,16 +7019,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalMessage(value); }
       }
       public Builder SetOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestRequired value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalMessage = true;
         result.optionalMessage_ = value;
         return this;
       }
       public Builder SetOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestRequired.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalMessage = true;
         result.optionalMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalMessage(global::Google.ProtocolBuffers.TestProtos.TestRequired value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalMessage &&
             result.optionalMessage_ != global::Google.ProtocolBuffers.TestProtos.TestRequired.DefaultInstance) {
             result.optionalMessage_ = global::Google.ProtocolBuffers.TestProtos.TestRequired.CreateBuilder(result.optionalMessage_).MergeFrom(value).BuildPartial();
@@ -7010,18 +7057,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedMessage(index);
       }
       public Builder SetRepeatedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestRequired value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessage_[index] = value;
         return this;
       }
       public Builder SetRepeatedMessage(int index, global::Google.ProtocolBuffers.TestProtos.TestRequired.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessage_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedMessage(global::Google.ProtocolBuffers.TestProtos.TestRequired value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessage_.Add(value);
         return this;
       }
       public Builder AddRepeatedMessage(global::Google.ProtocolBuffers.TestProtos.TestRequired.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessage_.Add(builderForValue.Build());
         return this;
       }
@@ -7239,16 +7290,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetForeignNested(value); }
       }
       public Builder SetForeignNested(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasForeignNested = true;
         result.foreignNested_ = value;
         return this;
       }
       public Builder SetForeignNested(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasForeignNested = true;
         result.foreignNested_ = builderForValue.Build();
         return this;
       }
       public Builder MergeForeignNested(global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasForeignNested &&
             result.foreignNested_ != global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.DefaultInstance) {
             result.foreignNested_ = global::Google.ProtocolBuffers.TestProtos.TestAllTypes.Types.NestedMessage.CreateBuilder(result.foreignNested_).MergeFrom(value).BuildPartial();
@@ -8013,16 +8067,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetA(value); }
       }
       public Builder SetA(global::Google.ProtocolBuffers.TestProtos.TestRecursiveMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasA = true;
         result.a_ = value;
         return this;
       }
       public Builder SetA(global::Google.ProtocolBuffers.TestProtos.TestRecursiveMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasA = true;
         result.a_ = builderForValue.Build();
         return this;
       }
       public Builder MergeA(global::Google.ProtocolBuffers.TestProtos.TestRecursiveMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasA &&
             result.a_ != global::Google.ProtocolBuffers.TestProtos.TestRecursiveMessage.DefaultInstance) {
             result.a_ = global::Google.ProtocolBuffers.TestProtos.TestRecursiveMessage.CreateBuilder(result.a_).MergeFrom(value).BuildPartial();
@@ -8243,16 +8300,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetBb(value); }
       }
       public Builder SetBb(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionB value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasBb = true;
         result.bb_ = value;
         return this;
       }
       public Builder SetBb(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionB.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasBb = true;
         result.bb_ = builderForValue.Build();
         return this;
       }
       public Builder MergeBb(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionB value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasBb &&
             result.bb_ != global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionB.DefaultInstance) {
             result.bb_ = global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionB.CreateBuilder(result.bb_).MergeFrom(value).BuildPartial();
@@ -8477,16 +8537,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetA(value); }
       }
       public Builder SetA(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionA value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasA = true;
         result.a_ = value;
         return this;
       }
       public Builder SetA(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionA.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasA = true;
         result.a_ = builderForValue.Build();
         return this;
       }
       public Builder MergeA(global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionA value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasA &&
             result.a_ != global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionA.DefaultInstance) {
             result.a_ = global::Google.ProtocolBuffers.TestProtos.TestMutualRecursionA.CreateBuilder(result.a_).MergeFrom(value).BuildPartial();
@@ -9163,16 +9226,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetFoo(value); }
       }
       public Builder SetFoo(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Foo value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasFoo = true;
         result.foo_ = value;
         return this;
       }
       public Builder SetFoo(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Foo.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasFoo = true;
         result.foo_ = builderForValue.Build();
         return this;
       }
       public Builder MergeFoo(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Foo value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasFoo &&
             result.foo_ != global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Foo.DefaultInstance) {
             result.foo_ = global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Foo.CreateBuilder(result.foo_).MergeFrom(value).BuildPartial();
@@ -9196,16 +9262,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetBar(value); }
       }
       public Builder SetBar(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Bar value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasBar = true;
         result.bar_ = value;
         return this;
       }
       public Builder SetBar(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Bar.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasBar = true;
         result.bar_ = builderForValue.Build();
         return this;
       }
       public Builder MergeBar(global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Bar value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasBar &&
             result.bar_ != global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Bar.DefaultInstance) {
             result.bar_ = global::Google.ProtocolBuffers.TestProtos.TestDupFieldNumber.Types.Bar.CreateBuilder(result.bar_).MergeFrom(value).BuildPartial();
@@ -9485,18 +9554,22 @@ namespace Google.ProtocolBuffers.TestProtos {
             return result.GetNestedmessageRepeatedForeignmessage(index);
           }
           public Builder SetNestedmessageRepeatedForeignmessage(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.nestedmessageRepeatedForeignmessage_[index] = value;
             return this;
           }
           public Builder SetNestedmessageRepeatedForeignmessage(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+            pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
             result.nestedmessageRepeatedForeignmessage_[index] = builderForValue.Build();
             return this;
           }
           public Builder AddNestedmessageRepeatedForeignmessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.nestedmessageRepeatedForeignmessage_.Add(value);
             return this;
           }
           public Builder AddNestedmessageRepeatedForeignmessage(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+            pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
             result.nestedmessageRepeatedForeignmessage_.Add(builderForValue.Build());
             return this;
           }
@@ -9677,16 +9750,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetOptionalNestedMessage(value); }
       }
       public Builder SetOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestNestedMessageHasBits.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptionalNestedMessage = true;
         result.optionalNestedMessage_ = value;
         return this;
       }
       public Builder SetOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestNestedMessageHasBits.Types.NestedMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptionalNestedMessage = true;
         result.optionalNestedMessage_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptionalNestedMessage(global::Google.ProtocolBuffers.TestProtos.TestNestedMessageHasBits.Types.NestedMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptionalNestedMessage &&
             result.optionalNestedMessage_ != global::Google.ProtocolBuffers.TestProtos.TestNestedMessageHasBits.Types.NestedMessage.DefaultInstance) {
             result.optionalNestedMessage_ = global::Google.ProtocolBuffers.TestProtos.TestNestedMessageHasBits.Types.NestedMessage.CreateBuilder(result.optionalNestedMessage_).MergeFrom(value).BuildPartial();
@@ -10179,6 +10255,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetStringField(value); }
       }
       public Builder SetStringField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasStringField = true;
         result.stringField_ = value;
         return this;
@@ -10215,16 +10292,19 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetMessageField(value); }
       }
       public Builder SetMessageField(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasMessageField = true;
         result.messageField_ = value;
         return this;
       }
       public Builder SetMessageField(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasMessageField = true;
         result.messageField_ = builderForValue.Build();
         return this;
       }
       public Builder MergeMessageField(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasMessageField &&
             result.messageField_ != global::Google.ProtocolBuffers.TestProtos.ForeignMessage.DefaultInstance) {
             result.messageField_ = global::Google.ProtocolBuffers.TestProtos.ForeignMessage.CreateBuilder(result.messageField_).MergeFrom(value).BuildPartial();
@@ -10248,6 +10328,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetStringPieceField(value); }
       }
       public Builder SetStringPieceField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasStringPieceField = true;
         result.stringPieceField_ = value;
         return this;
@@ -10266,6 +10347,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetCordField(value); }
       }
       public Builder SetCordField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasCordField = true;
         result.cordField_ = value;
         return this;
@@ -10312,10 +10394,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedStringField(index);
       }
       public Builder SetRepeatedStringField(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringField_[index] = value;
         return this;
       }
       public Builder AddRepeatedStringField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringField_.Add(value);
         return this;
       }
@@ -10364,18 +10448,22 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedMessageField(index);
       }
       public Builder SetRepeatedMessageField(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessageField_[index] = value;
         return this;
       }
       public Builder SetRepeatedMessageField(int index, global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessageField_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddRepeatedMessageField(global::Google.ProtocolBuffers.TestProtos.ForeignMessage value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedMessageField_.Add(value);
         return this;
       }
       public Builder AddRepeatedMessageField(global::Google.ProtocolBuffers.TestProtos.ForeignMessage.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.repeatedMessageField_.Add(builderForValue.Build());
         return this;
       }
@@ -10398,10 +10486,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedStringPieceField(index);
       }
       public Builder SetRepeatedStringPieceField(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringPieceField_[index] = value;
         return this;
       }
       public Builder AddRepeatedStringPieceField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedStringPieceField_.Add(value);
         return this;
       }
@@ -10424,10 +10514,12 @@ namespace Google.ProtocolBuffers.TestProtos {
         return result.GetRepeatedCordField(index);
       }
       public Builder SetRepeatedCordField(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedCordField_[index] = value;
         return this;
       }
       public Builder AddRepeatedCordField(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.repeatedCordField_.Add(value);
         return this;
       }
@@ -10671,6 +10763,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetMyString(value); }
       }
       public Builder SetMyString(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasMyString = true;
         result.myString_ = value;
         return this;
@@ -11009,6 +11102,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetEscapedBytes(value); }
       }
       public Builder SetEscapedBytes(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasEscapedBytes = true;
         result.escapedBytes_ = value;
         return this;
@@ -11099,6 +11193,7 @@ namespace Google.ProtocolBuffers.TestProtos {
         set { SetUtf8String(value); }
       }
       public Builder SetUtf8String(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasUtf8String = true;
         result.utf8String_ = value;
         return this;
diff --git a/src/ProtocolBuffers.Test/TestUtil.cs b/src/ProtocolBuffers.Test/TestUtil.cs
index d91d8540..47262ff9 100644
--- a/src/ProtocolBuffers.Test/TestUtil.cs
+++ b/src/ProtocolBuffers.Test/TestUtil.cs
@@ -1383,5 +1383,14 @@ namespace Google.ProtocolBuffers {
       }
       return bytes;
     }
+
+    internal static void AssertArgumentNullException(Action action) {
+      try {
+        action();
+        Assert.Fail("Exception was not thrown");
+      } catch (ArgumentNullException) {
+        // We expect this exception.
+      }
+    }
   }
 }
diff --git a/src/ProtocolBuffers.Test/TextFormatTest.cs b/src/ProtocolBuffers.Test/TextFormatTest.cs
index d8de4b8e..a8e0de4d 100644
--- a/src/ProtocolBuffers.Test/TextFormatTest.cs
+++ b/src/ProtocolBuffers.Test/TextFormatTest.cs
@@ -499,5 +499,29 @@ namespace Google.ProtocolBuffers {
       AssertFormatException(() => TextFormat.ParseUInt64("-1"));
       AssertFormatException(() => TextFormat.ParseInt32("abcd"));
     }
+
+    [Test]
+    public void ParseLongString() {
+      string longText =
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890" +
+        "123456789012345678901234567890123456789012345678901234567890";
+      TestAllTypes.Builder builder = TestAllTypes.CreateBuilder();
+      TextFormat.Merge("optional_string: \"" + longText + "\"", builder);
+      Assert.AreEqual(longText, builder.OptionalString);
+    }
   }
 }
diff --git a/src/ProtocolBuffers/DescriptorProtos/CSharpOptions.cs b/src/ProtocolBuffers/DescriptorProtos/CSharpOptions.cs
index 743a0c36..09733c3b 100644
--- a/src/ProtocolBuffers/DescriptorProtos/CSharpOptions.cs
+++ b/src/ProtocolBuffers/DescriptorProtos/CSharpOptions.cs
@@ -192,6 +192,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetNamespace(value); }
       }
       public Builder SetNamespace(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasNamespace = true;
         result.namespace_ = value;
         return this;
@@ -210,6 +211,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetUmbrellaClassname(value); }
       }
       public Builder SetUmbrellaClassname(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasUmbrellaClassname = true;
         result.umbrellaClassname_ = value;
         return this;
@@ -381,6 +383,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetPropertyName(value); }
       }
       public Builder SetPropertyName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasPropertyName = true;
         result.propertyName_ = value;
         return this;
diff --git a/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs b/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
index dcd10b8e..67fdf966 100644
--- a/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
+++ b/src/ProtocolBuffers/DescriptorProtos/DescriptorProtoFile.cs
@@ -379,18 +379,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetFile(index);
       }
       public Builder SetFile(int index, global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.file_[index] = value;
         return this;
       }
       public Builder SetFile(int index, global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.file_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddFile(global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.file_.Add(value);
         return this;
       }
       public Builder AddFile(global::Google.ProtocolBuffers.DescriptorProtos.FileDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.file_.Add(builderForValue.Build());
         return this;
       }
@@ -782,6 +786,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -800,6 +805,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetPackage(value); }
       }
       public Builder SetPackage(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasPackage = true;
         result.package_ = value;
         return this;
@@ -820,10 +826,12 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetDependency(index);
       }
       public Builder SetDependency(int index, string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.dependency_[index] = value;
         return this;
       }
       public Builder AddDependency(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.dependency_.Add(value);
         return this;
       }
@@ -846,18 +854,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetMessageType(index);
       }
       public Builder SetMessageType(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.messageType_[index] = value;
         return this;
       }
       public Builder SetMessageType(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.messageType_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddMessageType(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.messageType_.Add(value);
         return this;
       }
       public Builder AddMessageType(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.messageType_.Add(builderForValue.Build());
         return this;
       }
@@ -880,18 +892,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetEnumType(index);
       }
       public Builder SetEnumType(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.enumType_[index] = value;
         return this;
       }
       public Builder SetEnumType(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.enumType_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddEnumType(global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.enumType_.Add(value);
         return this;
       }
       public Builder AddEnumType(global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.enumType_.Add(builderForValue.Build());
         return this;
       }
@@ -914,18 +930,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetService(index);
       }
       public Builder SetService(int index, global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.service_[index] = value;
         return this;
       }
       public Builder SetService(int index, global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.service_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddService(global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.service_.Add(value);
         return this;
       }
       public Builder AddService(global::Google.ProtocolBuffers.DescriptorProtos.ServiceDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.service_.Add(builderForValue.Build());
         return this;
       }
@@ -948,18 +968,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetExtension(index);
       }
       public Builder SetExtension(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extension_[index] = value;
         return this;
       }
       public Builder SetExtension(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extension_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddExtension(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extension_.Add(value);
         return this;
       }
       public Builder AddExtension(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extension_.Add(builderForValue.Build());
         return this;
       }
@@ -980,16 +1004,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.FileOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.FileOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.FileOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.FileOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.FileOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -1601,6 +1628,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -1621,18 +1649,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetField(index);
       }
       public Builder SetField(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field_[index] = value;
         return this;
       }
       public Builder SetField(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.field_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddField(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.field_.Add(value);
         return this;
       }
       public Builder AddField(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.field_.Add(builderForValue.Build());
         return this;
       }
@@ -1655,18 +1687,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetExtension(index);
       }
       public Builder SetExtension(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extension_[index] = value;
         return this;
       }
       public Builder SetExtension(int index, global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extension_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddExtension(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extension_.Add(value);
         return this;
       }
       public Builder AddExtension(global::Google.ProtocolBuffers.DescriptorProtos.FieldDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extension_.Add(builderForValue.Build());
         return this;
       }
@@ -1689,18 +1725,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetNestedType(index);
       }
       public Builder SetNestedType(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.nestedType_[index] = value;
         return this;
       }
       public Builder SetNestedType(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.nestedType_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddNestedType(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.nestedType_.Add(value);
         return this;
       }
       public Builder AddNestedType(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.nestedType_.Add(builderForValue.Build());
         return this;
       }
@@ -1723,18 +1763,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetEnumType(index);
       }
       public Builder SetEnumType(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.enumType_[index] = value;
         return this;
       }
       public Builder SetEnumType(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.enumType_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddEnumType(global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.enumType_.Add(value);
         return this;
       }
       public Builder AddEnumType(global::Google.ProtocolBuffers.DescriptorProtos.EnumDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.enumType_.Add(builderForValue.Build());
         return this;
       }
@@ -1757,18 +1801,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetExtensionRange(index);
       }
       public Builder SetExtensionRange(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extensionRange_[index] = value;
         return this;
       }
       public Builder SetExtensionRange(int index, global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extensionRange_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddExtensionRange(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.extensionRange_.Add(value);
         return this;
       }
       public Builder AddExtensionRange(global::Google.ProtocolBuffers.DescriptorProtos.DescriptorProto.Types.ExtensionRange.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.extensionRange_.Add(builderForValue.Build());
         return this;
       }
@@ -1789,16 +1837,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.MessageOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.MessageOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.MessageOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.MessageOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.MessageOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -2200,6 +2251,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -2272,6 +2324,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetTypeName(value); }
       }
       public Builder SetTypeName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasTypeName = true;
         result.typeName_ = value;
         return this;
@@ -2290,6 +2343,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetExtendee(value); }
       }
       public Builder SetExtendee(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasExtendee = true;
         result.extendee_ = value;
         return this;
@@ -2308,6 +2362,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetDefaultValue(value); }
       }
       public Builder SetDefaultValue(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasDefaultValue = true;
         result.defaultValue_ = value;
         return this;
@@ -2326,16 +2381,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.FieldOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.FieldOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.FieldOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.FieldOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.FieldOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -2593,6 +2651,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -2613,18 +2672,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetValue(index);
       }
       public Builder SetValue(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.value_[index] = value;
         return this;
       }
       public Builder SetValue(int index, global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.value_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddValue(global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.value_.Add(value);
         return this;
       }
       public Builder AddValue(global::Google.ProtocolBuffers.DescriptorProtos.EnumValueDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.value_.Add(builderForValue.Build());
         return this;
       }
@@ -2645,16 +2708,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.EnumOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.EnumOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -2904,6 +2970,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -2940,16 +3007,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumValueOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumValueOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.EnumValueOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.EnumValueOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.EnumValueOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -3207,6 +3277,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -3227,18 +3298,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetMethod(index);
       }
       public Builder SetMethod(int index, global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.method_[index] = value;
         return this;
       }
       public Builder SetMethod(int index, global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.method_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddMethod(global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.method_.Add(value);
         return this;
       }
       public Builder AddMethod(global::Google.ProtocolBuffers.DescriptorProtos.MethodDescriptorProto.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.method_.Add(builderForValue.Build());
         return this;
       }
@@ -3259,16 +3334,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.ServiceOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.ServiceOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.ServiceOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.ServiceOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.ServiceOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -3540,6 +3618,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetName(value); }
       }
       public Builder SetName(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasName = true;
         result.name_ = value;
         return this;
@@ -3558,6 +3637,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetInputType(value); }
       }
       public Builder SetInputType(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasInputType = true;
         result.inputType_ = value;
         return this;
@@ -3576,6 +3656,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOutputType(value); }
       }
       public Builder SetOutputType(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOutputType = true;
         result.outputType_ = value;
         return this;
@@ -3594,16 +3675,19 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetOptions(value); }
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.MethodOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasOptions = true;
         result.options_ = value;
         return this;
       }
       public Builder SetOptions(global::Google.ProtocolBuffers.DescriptorProtos.MethodOptions.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.hasOptions = true;
         result.options_ = builderForValue.Build();
         return this;
       }
       public Builder MergeOptions(global::Google.ProtocolBuffers.DescriptorProtos.MethodOptions value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         if (result.HasOptions &&
             result.options_ != global::Google.ProtocolBuffers.DescriptorProtos.MethodOptions.DefaultInstance) {
             result.options_ = global::Google.ProtocolBuffers.DescriptorProtos.MethodOptions.CreateBuilder(result.options_).MergeFrom(value).BuildPartial();
@@ -3916,6 +4000,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetJavaPackage(value); }
       }
       public Builder SetJavaPackage(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasJavaPackage = true;
         result.javaPackage_ = value;
         return this;
@@ -3934,6 +4019,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetJavaOuterClassname(value); }
       }
       public Builder SetJavaOuterClassname(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasJavaOuterClassname = true;
         result.javaOuterClassname_ = value;
         return this;
@@ -3990,18 +4076,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -4250,18 +4340,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -4545,6 +4639,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetExperimentalMapKey(value); }
       }
       public Builder SetExperimentalMapKey(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasExperimentalMapKey = true;
         result.experimentalMapKey_ = value;
         return this;
@@ -4565,18 +4660,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -4785,18 +4884,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -5005,18 +5108,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -5225,18 +5332,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -5445,18 +5556,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetUninterpretedOption(index);
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_[index] = value;
         return this;
       }
       public Builder SetUninterpretedOption(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.uninterpretedOption_.Add(value);
         return this;
       }
       public Builder AddUninterpretedOption(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.uninterpretedOption_.Add(builderForValue.Build());
         return this;
       }
@@ -5699,6 +5814,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
             set { SetNamePart_(value); }
           }
           public Builder SetNamePart_(string value) {
+            pb::ThrowHelper.ThrowIfNull(value, "value");
             result.hasNamePart_ = true;
             result.namePart_ = value;
             return this;
@@ -6010,18 +6126,22 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         return result.GetName(index);
       }
       public Builder SetName(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.name_[index] = value;
         return this;
       }
       public Builder SetName(int index, global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.name_[index] = builderForValue.Build();
         return this;
       }
       public Builder AddName(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.name_.Add(value);
         return this;
       }
       public Builder AddName(global::Google.ProtocolBuffers.DescriptorProtos.UninterpretedOption.Types.NamePart.Builder builderForValue) {
+        pb::ThrowHelper.ThrowIfNull(builderForValue, "builderForValue");
         result.name_.Add(builderForValue.Build());
         return this;
       }
@@ -6042,6 +6162,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetIdentifierValue(value); }
       }
       public Builder SetIdentifierValue(string value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasIdentifierValue = true;
         result.identifierValue_ = value;
         return this;
@@ -6114,6 +6235,7 @@ namespace Google.ProtocolBuffers.DescriptorProtos {
         set { SetStringValue(value); }
       }
       public Builder SetStringValue(pb::ByteString value) {
+        pb::ThrowHelper.ThrowIfNull(value, "value");
         result.hasStringValue = true;
         result.stringValue_ = value;
         return this;
diff --git a/src/ProtocolBuffers/FieldAccess/RepeatedEnumAccessor.cs b/src/ProtocolBuffers/FieldAccess/RepeatedEnumAccessor.cs
index c85f3f57..38396093 100644
--- a/src/ProtocolBuffers/FieldAccess/RepeatedEnumAccessor.cs
+++ b/src/ProtocolBuffers/FieldAccess/RepeatedEnumAccessor.cs
@@ -66,10 +66,12 @@ namespace Google.ProtocolBuffers.FieldAccess {
     }
 
     public override void AddRepeated(TBuilder builder, object value) {
-      base.AddRepeated(builder, ((EnumValueDescriptor) value).Number);
+      ThrowHelper.ThrowIfNull(value, "value");
+      base.AddRepeated(builder, ((EnumValueDescriptor)value).Number);
     }
 
     public override void SetRepeated(TBuilder builder, int index, object value) {
+      ThrowHelper.ThrowIfNull(value, "value");
       base.SetRepeated(builder, index, ((EnumValueDescriptor) value).Number);
     }
   }
diff --git a/src/ProtocolBuffers/FieldAccess/RepeatedMessageAccessor.cs b/src/ProtocolBuffers/FieldAccess/RepeatedMessageAccessor.cs
index 0a4d516e..5cca9748 100644
--- a/src/ProtocolBuffers/FieldAccess/RepeatedMessageAccessor.cs
+++ b/src/ProtocolBuffers/FieldAccess/RepeatedMessageAccessor.cs
@@ -64,7 +64,7 @@ namespace Google.ProtocolBuffers.FieldAccess {
     /// which may already be of the right type or may be a dynamic message.
     /// </summary>
     private object CoerceType(object value) {
-
+      ThrowHelper.ThrowIfNull(value, "value");
       // If it's already of the right type, we're done
       if (ClrType.IsInstanceOfType(value)) {
         return value;
diff --git a/src/ProtocolBuffers/FieldAccess/RepeatedPrimitiveAccessor.cs b/src/ProtocolBuffers/FieldAccess/RepeatedPrimitiveAccessor.cs
index 2acf8e2a..e5bb411a 100644
--- a/src/ProtocolBuffers/FieldAccess/RepeatedPrimitiveAccessor.cs
+++ b/src/ProtocolBuffers/FieldAccess/RepeatedPrimitiveAccessor.cs
@@ -122,10 +122,12 @@ namespace Google.ProtocolBuffers.FieldAccess {
     }
 
     public virtual void SetRepeated(TBuilder builder, int index, object value) {
-      setElementMethod.Invoke(builder, new object[] {index, value} );
+      ThrowHelper.ThrowIfNull(value, "value");
+      setElementMethod.Invoke(builder, new object[] { index, value });
     }
 
     public virtual void AddRepeated(TBuilder builder, object value) {
+      ThrowHelper.ThrowIfNull(value, "value");
       addValueDelegate(builder, value);
     }
 
diff --git a/src/ProtocolBuffers/FieldAccess/SingleEnumAccessor.cs b/src/ProtocolBuffers/FieldAccess/SingleEnumAccessor.cs
index 8ecde10f..9125bdcc 100644
--- a/src/ProtocolBuffers/FieldAccess/SingleEnumAccessor.cs
+++ b/src/ProtocolBuffers/FieldAccess/SingleEnumAccessor.cs
@@ -63,6 +63,7 @@ namespace Google.ProtocolBuffers.FieldAccess {
     /// from an EnumValueDescriptor parameter.
     /// </summary>
     public override void SetValue(TBuilder builder, object value) {
+      ThrowHelper.ThrowIfNull(value, "value");
       EnumValueDescriptor valueDescriptor = (EnumValueDescriptor) value;
       base.SetValue(builder, valueDescriptor.Number);
     }
diff --git a/src/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs b/src/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs
index 761d7c96..9ce2cbb1 100644
--- a/src/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs
+++ b/src/ProtocolBuffers/FieldAccess/SingleMessageAccessor.cs
@@ -60,7 +60,7 @@ namespace Google.ProtocolBuffers.FieldAccess {
     /// which may already be of the right type or may be a dynamic message.
     /// </summary>
     private object CoerceType(object value) {
-
+      ThrowHelper.ThrowIfNull(value, "value");
       // If it's already of the right type, we're done
       if (ClrType.IsInstanceOfType(value)) {
         return value;
diff --git a/src/ProtocolBuffers/FieldSet.cs b/src/ProtocolBuffers/FieldSet.cs
index a2e1912a..bc2e2e70 100644
--- a/src/ProtocolBuffers/FieldSet.cs
+++ b/src/ProtocolBuffers/FieldSet.cs
@@ -413,7 +413,9 @@ namespace Google.ProtocolBuffers {
     /// element type, not whether it's a list.
     /// </remarks>
     /// <exception cref="ArgumentException">The value is not of the right type.</exception>
+    /// <exception cref="ArgumentNullException">The value is null.</exception>
     private static void VerifyType(FieldDescriptor field, object value) {
+      ThrowHelper.ThrowIfNull(value, "value");
       bool isValid = false;
       switch (field.MappedType) {
         case MappedType.Int32:       isValid = value is int;    break;
diff --git a/src/ProtocolBuffers/GeneratedBuilder.cs b/src/ProtocolBuffers/GeneratedBuilder.cs
index 90767929..c678d66f 100644
--- a/src/ProtocolBuffers/GeneratedBuilder.cs
+++ b/src/ProtocolBuffers/GeneratedBuilder.cs
@@ -78,7 +78,13 @@ namespace Google.ProtocolBuffers {
     /// <summary>
     /// Adds all of the specified values to the given collection.
     /// </summary>
+    /// <exception cref="ArgumentNullException">Any element of the list is null</exception>
     protected void AddRange<T>(IEnumerable<T> source, IList<T> destination) {
+      ThrowHelper.ThrowIfNull(source);
+      // We only need to check this for nullable types.
+      if (default(T) == null) {
+        ThrowHelper.ThrowIfAnyNull(source);
+      }
       List<T> list = destination as List<T>;
       if (list != null) {
         list.AddRange(source);
diff --git a/src/ProtocolBuffers/ProtocolBuffers.csproj b/src/ProtocolBuffers/ProtocolBuffers.csproj
index 520594f5..5a1419e1 100644
--- a/src/ProtocolBuffers/ProtocolBuffers.csproj
+++ b/src/ProtocolBuffers/ProtocolBuffers.csproj
@@ -104,6 +104,7 @@
     <Compile Include="TextFormat.cs" />
     <Compile Include="TextGenerator.cs" />
     <Compile Include="TextTokenizer.cs" />
+    <Compile Include="ThrowHelper.cs" />
     <Compile Include="UninitializedMessageException.cs" />
     <Compile Include="UnknownField.cs" />
     <Compile Include="UnknownFieldSet.cs" />
diff --git a/src/ProtocolBuffers/ThrowHelper.cs b/src/ProtocolBuffers/ThrowHelper.cs
new file mode 100644
index 00000000..2adede61
--- /dev/null
+++ b/src/ProtocolBuffers/ThrowHelper.cs
@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Google.ProtocolBuffers {
+  /// <summary>
+  /// Helper methods for throwing exceptions
+  /// </summary>
+  public static class ThrowHelper {
+
+    /// <summary>
+    /// Throws an ArgumentNullException if the given value is null.
+    /// </summary>
+    public static void ThrowIfNull(object value, string name) {
+      if (value == null) {
+        throw new ArgumentNullException(name);
+      }
+    }
+
+    /// <summary>
+    /// Throws an ArgumentNullException if the given value is null.
+    /// </summary>
+    public static void ThrowIfNull(object value) {
+      if (value == null) {
+        throw new ArgumentNullException();
+      }
+    }
+
+    /// <summary>
+    /// Throws an ArgumentNullException if the given value or any element within it is null.
+    /// </summary>
+    public static void ThrowIfAnyNull<T>(IEnumerable<T> sequence) {
+      foreach (T t in sequence) {
+        if (t == null) {
+          throw new ArgumentNullException();
+        }
+      }
+    }
+  }
+}