diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 4c11f38..24073df 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -538,7 +538,7 @@
 
   // Set or check the various bits in the IdentifierInfo structure.
   // Token IDs are read-only.
-  if (HasRevertedTokenIDToIdentifier)
+  if (HasRevertedTokenIDToIdentifier && II->getTokenID() != tok::identifier)
     II->RevertTokenIDToIdentifier();
   II->setObjCOrBuiltinID(ObjCOrBuiltinID);
   assert(II->isExtensionToken() == ExtensionToken &&