diff --git a/lib/models/Courseware/StructuralElement.php b/lib/models/Courseware/StructuralElement.php
index ee5e92a79c8a4c9a0da08a7ea60807596aae6a75..69d9d22da624d9ebfc720f113f9568fcabbee78a 100755
--- a/lib/models/Courseware/StructuralElement.php
+++ b/lib/models/Courseware/StructuralElement.php
@@ -797,7 +797,7 @@ SQL;
         return $doc;
     }
 
-    private function getElementPdfExport(string $parent_name = '', bool $with_children, $user)
+    private function getElementPdfExport(string $parent_name, bool $with_children, $user)
     {
         if (!$this->canRead($user)) {
             return '';