diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 8b98cba..183d9a9 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -205,7 +205,8 @@
 
   if (BID == Builtin::BI__builtin_va_start ||
       BID == Builtin::BI__builtin_va_copy ||
-      BID == Builtin::BI__builtin_va_end)
+      BID == Builtin::BI__builtin_va_end ||
+      BID == Builtin::BI__builtin_stdarg_start)
     InitBuiltinVaListType();
     
   QualType R = Context.BuiltinInfo.GetBuiltinType(BID, Context);