diff --git a/src/workflow/ArcanistDiffWorkflow.php b/src/workflow/ArcanistDiffWorkflow.php
--- a/src/workflow/ArcanistDiffWorkflow.php
+++ b/src/workflow/ArcanistDiffWorkflow.php
@@ -2361,7 +2361,7 @@
 
     // If we track an upstream branch either directly or indirectly, use that.
     $branch = $api->getBranchName();
-    if (strlen($branch)) {
+    if (phutil_nonempty_string($branch)) {
       $upstream_path = $api->getPathToUpstream($branch);
       $remote_branch = $upstream_path->getRemoteBranchName();
       if ($remote_branch !== null) {