3 files changed, 26 insertions, 4 deletions
diff --git a/test/files/neg/javaConversions-2.10-ambiguity.check b/test/files/neg/javaConversions-2.10-ambiguity.check
new file mode 100644
index 0000000000..c064a22964
--- /dev/null
+++ b/test/files/neg/javaConversions-2.10-ambiguity.check
@@ -0,0 +1,6 @@
+javaConversions-2.10-ambiguity.scala:8: error: type mismatch;
+ found   : scala.collection.concurrent.Map[String,String]
+ required: scala.collection.mutable.ConcurrentMap[String,String]
+  assertType[mutable.ConcurrentMap[String, String]](a)
+                                                    ^
+one error found
diff --git a/test/files/neg/javaConversions-2.10-ambiguity.scala b/test/files/neg/javaConversions-2.10-ambiguity.scala
new file mode 100644
index 0000000000..e856846a29
--- /dev/null
+++ b/test/files/neg/javaConversions-2.10-ambiguity.scala
@@ -0,0 +1,10 @@
+import collection.{JavaConversions, mutable, concurrent}
+import JavaConversions._
+import java.util.concurrent.{ConcurrentHashMap => CHM}
+
+object Bar {
+  def assertType[T](t: T) = t
+  val a = new CHM[String, String]() += (("", ""))
+  assertType[mutable.ConcurrentMap[String, String]](a)
+}
+// vim: set et:
diff --git a/test/files/pos/javaConversions-2.10-regression.scala b/test/files/pos/javaConversions-2.10-regression.scala
index 619c44b46d..e1b81015ba 100644
--- a/test/files/pos/javaConversions-2.10-regression.scala
+++ b/test/files/pos/javaConversions-2.10-regression.scala
@@ -1,11 +1,17 @@
-import collection.{JavaConversions, mutable}
+import collection.{JavaConversions, mutable, concurrent}
 import JavaConversions._
-import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.{ConcurrentHashMap => CHM}
 
 object Foo {
   def buildCache2_9_simple[K <: AnyRef, V <: AnyRef]: mutable.ConcurrentMap[K, V] =
-    asScalaConcurrentMap(new ConcurrentHashMap())
+    asScalaConcurrentMap(new CHM())
 
   def buildCache2_9_implicit[K <: AnyRef, V <: AnyRef]: mutable.ConcurrentMap[K, V] =
-    new ConcurrentHashMap[K, V]()
+    new CHM[K, V]()
+}
+
+object Bar {
+  def assertType[T](t: T) = t
+  val a = new CHM[String, String]() += (("", ""))
+  assertType[concurrent.Map[String, String]](a)
 }