diff --git a/unittests/ADT/StringRefTest.cpp b/unittests/ADT/StringRefTest.cpp
index 7e4d0dcd413..5731e4abaf1 100644
--- a/unittests/ADT/StringRefTest.cpp
+++ b/unittests/ADT/StringRefTest.cpp
@@ -16,7 +16,7 @@ using namespace llvm;
 namespace llvm {
 
 std::ostream &operator<<(std::ostream &OS, const StringRef &S) {
-  OS << S;
+  OS << S.str();
   return OS;
 }