diff --git a/sql/item.h b/sql/item.h
index 798abb5112a..fd4b8cb3e14 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2890,7 +2890,7 @@ public:
 
   bool walk(Item_processor processor, bool walk_subquery, uchar *args)
   {
-    return arg->walk(processor, walk_subquery, args) ||
+    return (arg && arg->walk(processor, walk_subquery, args)) ||
       (this->*processor)(args);
   }