diff --git a/src/applications/auth/management/PhabricatorAuthManagementRefreshWorkflow.php b/src/applications/auth/management/PhabricatorAuthManagementRefreshWorkflow.php
--- a/src/applications/auth/management/PhabricatorAuthManagementRefreshWorkflow.php
+++ b/src/applications/auth/management/PhabricatorAuthManagementRefreshWorkflow.php
@@ -34,7 +34,7 @@
         ));
 
     $username = $args->getArg('user');
-    if (strlen($username)) {
+    if (phutil_nonempty_string($username)) {
       $user = id(new PhabricatorPeopleQuery())
         ->setViewer($viewer)
         ->withUsernames(array($username))