diff --git a/mod/quiz/db/upgrade.php b/mod/quiz/db/upgrade.php
index 2861328df6d..d3a8e72c382 100644
--- a/mod/quiz/db/upgrade.php
+++ b/mod/quiz/db/upgrade.php
@@ -113,7 +113,7 @@ function xmldb_quiz_upgrade($oldversion) {
         // Get a list of response variables that have files.
         require_once($CFG->dirroot . '/question/type/questiontypebase.php');
         $variables = array();
-        foreach (get_plugin_list('qtype') as $plugin => $path) {
+        foreach (get_plugin_list('qtype') as $qtypename => $path) {
             $file = $path . '/questiontype.php';
             if (!is_readable($file)) {
                 continue;