diff --git a/dm/dm.go b/dm/dm.go
index 152e792dc..ebed53b6f 100644
--- a/dm/dm.go
+++ b/dm/dm.go
@@ -120,6 +120,10 @@ func getGithubCredential() *common.RegistryCredential {
 	return nil
 }
 
+func init() {
+	flag.Usage = usage
+}
+
 func main() {
 	defer func() {
 		result := recover()