diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp
index 9e59a0a5a2f7..c8e3d88e00e1 100644
--- a/clang/lib/CodeGen/CGCXX.cpp
+++ b/clang/lib/CodeGen/CGCXX.cpp
@@ -1658,7 +1658,8 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD) {
         else {
           // Initializing an anonymous union data member.
           FieldDecl *anonMember = Member->getAnonUnionMember();
-          LHS = EmitLValueForField(LHS.getAddress(), anonMember, false, 0);
+          LHS = EmitLValueForField(LHS.getAddress(), anonMember, 
+                                   /*IsUnion=*/true, 0);
           FieldType = anonMember->getType();
         }
       }
diff --git a/clang/test/CodeGenCXX/anonymous-union-member-initializer.cpp b/clang/test/CodeGenCXX/anonymous-union-member-initializer.cpp
new file mode 100644
index 000000000000..2030f4053c90
--- /dev/null
+++ b/clang/test/CodeGenCXX/anonymous-union-member-initializer.cpp
@@ -0,0 +1,12 @@
+// RUN: clang-cc -emit-llvm -o - %s
+
+struct A {
+  union {
+    int a;
+    void* b;
+  };
+  
+  A() : a(0) { }
+};
+
+A a;