--- a/commands/pm/version_control/backup.inc
+++ b/commands/pm/version_control/backup.inc
@@ -12,7 +12,7 @@
    */
   public function pre_update(&$project, $items_to_test = array()) {
     if (drush_get_option('no-backup', FALSE)) {
-      return;
+      return TRUE;
     }
     if ($backup_target = $this->prepare_backup_dir()) {
       if ($project['project_type'] != 'core') {