diff --git a/daemon/debug.c b/daemon/debug.c
index 2ba48a73b..6b9d75628 100644
--- a/daemon/debug.c
+++ b/daemon/debug.c
@@ -92,7 +92,7 @@ do_debug (const char *subcmd, char *const *argv)
       return cmds[i].f (subcmd, argc, argv);
   }
 
-  reply_with_error ("use 'debug help' to list the supported commands");
+  reply_with_error ("use 'debug help 0' to list the supported commands");
   return NULL;
 }