diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 38f5008..bde03a7 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -138,6 +138,7 @@
     union {
       unsigned char PointerAlignInBytes;
       unsigned char PointerSizeInBytes;
+      unsigned char SizeSizeInBytes;     // sizeof(size_t)
     };
   };