diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 6d98952..b5a234c 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -793,6 +793,10 @@
     return false;
   }
 
+  // sizeof (objc class) ?
+  if (SrcTy->isObjCInterfaceType())
+    return false;
+  
   bool isSizeOf = E->isSizeOf();
   
   // GCC extension: sizeof(function) = 1.