diff --git a/src/structs.h b/src/structs.h
index 18915cf..b9792b1 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1957,7 +1957,7 @@
     char_u	*actext;	    /* accelerator text (after TAB) */
     int		priority;	    /* Menu order priority */
 #ifdef FEAT_GUI
-    void	(*cb)();	    /* Call-back routine */
+    void	(*cb) __ARGS((vimmenu_T *));	    /* Call-back routine */
 #endif
 #ifdef FEAT_TOOLBAR
     char_u	*iconfile;	    /* name of file for icon or NULL */