diff --git a/trigger/categories/lib.php b/trigger/categories/lib.php
index 60405b546f75e9f7a5282abf59df74b0743fdf24..38737e7d448eef5a9c3885f51a7ce6c810490077 100644
--- a/trigger/categories/lib.php
+++ b/trigger/categories/lib.php
@@ -117,7 +117,7 @@ class categories extends base_automatic {
      * @throws \dml_exception
      */
     public function extend_add_instance_form_definition($mform) {
-        global $DB;
+        
         $displaylist = core_course_category::make_categories_list();
         
         $options = array(