diff --git a/ir.h b/ir.h
index fee23b25829..13d07155a42 100644
--- a/ir.h
+++ b/ir.h
@@ -156,6 +156,11 @@ public:
     */
    unsigned array_lvalue:1;
 
+   /**
+    * Emit a warning if this variable is accessed.
+    */
+   const char *warn_extension;
+
    /**
     * Value assigned in the initializer of a variable declared "const"
     */