diff --git a/include/clang/Basic/DiagnosticKinds.def b/include/clang/Basic/DiagnosticKinds.def
index 664d3af..259265c 100644
--- a/include/clang/Basic/DiagnosticKinds.def
+++ b/include/clang/Basic/DiagnosticKinds.def
@@ -606,7 +606,7 @@
      "expected unqualified-id")
 DIAG(err_no_declarators, ERROR,
      "declaration does not declare anything")
-DIAG(warn_no_declarators, WARNING,
+DIAG(ext_typedef_without_a_name, EXTWARN,
      "typedef requires a name")
 DIAG(err_func_def_no_params, ERROR,
      "function definition does not declare parameters")
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index dbf1e7b..276f2e2 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -736,11 +736,12 @@
       return Tag;
   }
 
-  // Permit typedefs without declarators as a Microsoft extension.
   if (!DS.isMissingDeclaratorOk()) {
+    // Warn about typedefs of enums without names, since this is an
+    // extension in both Microsoft an GNU.
     if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef &&
         Tag && isa<EnumDecl>(Tag)) {
-      Diag(DS.getSourceRange().getBegin(), diag::warn_no_declarators)
+      Diag(DS.getSourceRange().getBegin(), diag::ext_typedef_without_a_name)
         << DS.getSourceRange();
       return Tag;
     }