6 files changed, 33 insertions, 0 deletions
diff --git a/test/files/neg/t0903.check b/test/files/neg/t0903.check
index 2dd05cd3ee..f9dc28bf16 100644
--- a/test/files/neg/t0903.check
+++ b/test/files/neg/t0903.check
@@ -1,4 +1,5 @@
 t0903.scala:3: error: value += is not a member of Int
+  Expression does not convert to assignment because receiver is not assignable.
   x += 1
     ^
 t0903.scala:4: error: reassignment to val
diff --git a/test/files/neg/t1215.check b/test/files/neg/t1215.check
index 1f9dd6bf38..4cbd0d85f3 100644
--- a/test/files/neg/t1215.check
+++ b/test/files/neg/t1215.check
@@ -1,4 +1,5 @@
 t1215.scala:2: error: value += is not a member of Int
+  Expression does not convert to assignment because receiver is not assignable.
   val x = 1 += 1
             ^
 one error found
diff --git a/test/files/neg/t8763.check b/test/files/neg/t8763.check
new file mode 100644
index 0000000000..4659e57be6
--- /dev/null
+++ b/test/files/neg/t8763.check
@@ -0,0 +1,6 @@
+t8763.scala:9: error: type mismatch;
+ found   : Char
+ required: String
+    names_times(fields(0)) += fields(1).toLong
+                      ^
+one error found
diff --git a/test/files/neg/t8763.scala b/test/files/neg/t8763.scala
new file mode 100644
index 0000000000..08ce1b471a
--- /dev/null
+++ b/test/files/neg/t8763.scala
@@ -0,0 +1,11 @@
+
+import collection.mutable
+
+object Foo {
+  def bar() {
+    val names_times = mutable.Map[String, mutable.Set[Long]]()
+    val line = ""
+    val Array(fields) = line.split("\t")
+    names_times(fields(0)) += fields(1).toLong
+  }
+}
diff --git a/test/files/neg/t9834.check b/test/files/neg/t9834.check
new file mode 100644
index 0000000000..eaf85abdcd
--- /dev/null
+++ b/test/files/neg/t9834.check
@@ -0,0 +1,8 @@
+t9834.scala:5: error: value += is not a member of Int
+  Expression does not convert to assignment because:
+    type mismatch;
+     found   : String
+     required: Int
+  x() += "42"
+      ^
+one error found
diff --git a/test/files/neg/t9834.scala b/test/files/neg/t9834.scala
new file mode 100644
index 0000000000..1ecda7a2b8
--- /dev/null
+++ b/test/files/neg/t9834.scala
@@ -0,0 +1,6 @@
+
+object x { def apply() = 42 ; def update(i: Int) = () }
+
+trait Test {
+  x() += "42"
+}