diff --git a/include/llvm/IR/DerivedTypes.h b/include/llvm/IR/DerivedTypes.h
index 6c00f596bad..e279e60e476 100644
--- a/include/llvm/IR/DerivedTypes.h
+++ b/include/llvm/IR/DerivedTypes.h
@@ -117,7 +117,7 @@ public:
   /// argument type.
   static bool isValidArgumentType(Type *ArgTy);
 
-  bool isVarArg() const { return getSubclassData(); }
+  bool isVarArg() const { return getSubclassData()!=0; }
   Type *getReturnType() const { return ContainedTys[0]; }
 
   typedef Type::subtype_iterator param_iterator;