diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 51fa330..08dc993 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -1251,6 +1251,9 @@
       AsBytes.push_back(Val & 0xFF);
     }
   }
+  // Append one extra null character, the second is automatically added by our
+  // caller.
+  AsBytes.push_back(0);
 
   IsUTF16 = true;
   return Map.GetOrCreateValue(llvm::StringRef(AsBytes.data(), AsBytes.size()));