diff --git a/question/type/datasetdependent/datasetitems_form.php b/question/type/datasetdependent/datasetitems_form.php
index aafc08b1396..17bf387e6a9 100644
--- a/question/type/datasetdependent/datasetitems_form.php
+++ b/question/type/datasetdependent/datasetitems_form.php
@@ -81,7 +81,7 @@ class question_dataset_dependent_items_form extends moodleform {
         foreach ($this->datasetdefs as $defkey => $datasetdef){
             $mform->addElement('text', "number[$j]", get_string('param', 'qtype_datasetdependent', $datasetdef->name));
             $mform->setType("number[$j]", PARAM_NUMBER);
-            $this->qtypeobj->custom_generator_tools_part(&$mform, $idx, $j);
+            $this->qtypeobj->custom_generator_tools_part($mform, $idx, $j);
             $idx++;
             $mform->addElement('hidden', "definition[$j]");
             $mform->setType("definition[$j]", PARAM_RAW);