diff --git a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
--- a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
+++ b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
@@ -1137,7 +1137,8 @@
     $viewer = $this->requireViewer();
 
     $query_key = $request->getValue('queryKey');
-    if (!strlen($query_key)) {
+    $is_empty_query_key = phutil_string_cast($query_key) === '';
+    if ($is_empty_query_key) {
       $saved_query = new PhabricatorSavedQuery();
     } else if ($this->isBuiltinQuery($query_key)) {
       $saved_query = $this->buildSavedQueryFromBuiltin($query_key);