Index: cfe/trunk/unittests/Tooling/TestVisitor.h
===================================================================
--- cfe/trunk/unittests/Tooling/TestVisitor.h
+++ cfe/trunk/unittests/Tooling/TestVisitor.h
@@ -53,7 +53,10 @@
   bool runOver(StringRef Code, Language L = Lang_CXX) {
     std::vector<std::string> Args;
     switch (L) {
-      case Lang_C: Args.push_back("-std=c99"); break;
+      case Lang_C:
+        Args.push_back("-x");
+        Args.push_back("c");
+        break;
       case Lang_CXX98: Args.push_back("-std=c++98"); break;
       case Lang_CXX11: Args.push_back("-std=c++11"); break;
       case Lang_CXX14: Args.push_back("-std=c++14"); break;