diff --git a/src/Form/PanelsAddBlockForm.php b/src/Form/PanelsAddBlockForm.php
index f4cc8c7d7..1d9cccbec 100644
--- a/src/Form/PanelsAddBlockForm.php
+++ b/src/Form/PanelsAddBlockForm.php
@@ -62,7 +62,7 @@ protected function prepareBlock($plugin_id) {
   /**
    * {@inheritdoc}
    */
-  public function buildForm(array $form, FormStateInterface $form_state, $tempstore_id = NULL, $machine_name = NULL, $block_id = NULL, Request $request = NULL) {
+  public function buildForm(array $form, FormStateInterface $form_state, $tempstore_id = NULL, $machine_name = NULL, $block_id = NULL, ?Request $request = NULL) {
     $form = parent::buildForm($form, $form_state, $tempstore_id, $machine_name, $block_id);
     $form['region']['#default_value'] = $request->query->get('region');
     return $form;