1 files changed, 1 insertions, 1 deletions

diff --git a/src/menu.c b/src/menu.c
index 9504cee5923..737f2b55e8b 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -408,7 +408,7 @@ single_menu_item (Lisp_Object key, Lisp_Object item, Lisp_Object dummy, void *sk
 
       if (prefix)
         {
-          AUTO_STRING (prefix_obj, prefix);
+          AUTO_STRING_WITH_LEN (prefix_obj, prefix, 4);
           item_string = concat2 (prefix_obj, item_string);
         }
   }