diff --git a/core/modules/views_ui/src/Form/Ajax/ViewsFormBase.php b/core/modules/views_ui/src/Form/Ajax/ViewsFormBase.php
index f905060..dc7cb16 100644
--- a/core/modules/views_ui/src/Form/Ajax/ViewsFormBase.php
+++ b/core/modules/views_ui/src/Form/Ajax/ViewsFormBase.php
@@ -147,6 +147,7 @@ public function getForm(ViewStorageInterface $view, $display_id, $js) {
       // Build the new form state for the next form in the stack.
       $reflection = new \ReflectionClass($view::$forms[$top[1]]);
       $form_state = $reflection->newInstanceArgs(array_slice($top, 3, 2))->getFormState($view, $top[2], $form_state['ajax']);
+      $form_class = get_class($form_state['build_info']['callback_object']);
 
       $form_state['input'] = array();
       $form_path = views_ui_build_form_path($form_state);