diff --git a/modules/mod_articles_categories/mod_articles_categories.php b/modules/mod_articles_categories/mod_articles_categories.php
index 374b85f4553e7..7eefcf8d3fc55 100644
--- a/modules/mod_articles_categories/mod_articles_categories.php
+++ b/modules/mod_articles_categories/mod_articles_categories.php
@@ -12,7 +12,9 @@
 // Include the helper functions only once
 require_once __DIR__ . '/helper.php';
 
-$cacheid = md5(serialize($module->module));
+JLoader::register('JCategoryNode', JPATH_BASE . '/libraries/legacy/categories/categories.php');
+
+$cacheid = md5($module->id);
 
 $cacheparams = new stdClass;
 $cacheparams->cachemode = 'id';