diff --git a/path_breadcrumbs_ui/path_breadcrumbs_ui.module b/path_breadcrumbs_ui/path_breadcrumbs_ui.module
index 1c89204..16ddfe0 100644
--- a/path_breadcrumbs_ui/path_breadcrumbs_ui.module
+++ b/path_breadcrumbs_ui/path_breadcrumbs_ui.module
@@ -943,10 +943,10 @@ function _path_breadcrumbs_ui_form_apply_default_values(&$form, $machine_name) {
  *   Form which will be added to the button.
  * @param array $buttons
  *   Array with buttons that should be added ('prev', 'next', 'finish').
- * @param $form_name
+ * @param string $form_name
  *   Name of form that addes buttons.
  */
-function _path_breadcrumbs_ui_form_attach_buttons(&$form, $buttons = array(), $form_name) {
+function _path_breadcrumbs_ui_form_attach_buttons(&$form, array $buttons = array(), string $form_name = '') {
 
   if ($form_name == 'path_breadcrumbs_ui_add_form' || $form_name == 'path_breadcrumbs_ui_edit_form') {
     $form_wrapper = 'path-breadcrumbs-ui-form';