diff --git a/weed/filer/mongodb/mongodb_store.go b/weed/filer/mongodb/mongodb_store.go
index f87878f08..cbdfe7f54 100644
--- a/weed/filer/mongodb/mongodb_store.go
+++ b/weed/filer/mongodb/mongodb_store.go
@@ -74,10 +74,15 @@ func (store *MongodbStore) connection(uri string, poolSize uint64, ssl bool, ssl
 	}
 
 	if username != "" && password != "" {
-		creds := options.Credential{
-			Username: username,
-			Password: password,
+		// Keep auth fields parsed from the URI (AuthSource, AuthMechanism, ...)
+		// and only override the credentials.
+		creds := options.Credential{}
+		if opts.Auth != nil {
+			creds = *opts.Auth
 		}
+		creds.Username = username
+		creds.Password = password
+		creds.PasswordSet = true
 		opts.SetAuth(creds)
 	}