diff --git a/modules/backend/widgets/Form.php b/modules/backend/widgets/Form.php
index 654e20c01..f0d84e2d6 100644
--- a/modules/backend/widgets/Form.php
+++ b/modules/backend/widgets/Form.php
@@ -832,6 +832,8 @@ class Form extends WidgetBase
      */
     public function getSaveData()
     {
+        $this->defineFormFields();
+
         $result = [];
 
         /*