diff --git a/lib/filestorage/file_storage.php b/lib/filestorage/file_storage.php
index f22635fc5bd..ee29b75f6a1 100644
--- a/lib/filestorage/file_storage.php
+++ b/lib/filestorage/file_storage.php
@@ -2015,6 +2015,7 @@ class file_storage {
      */
     public function cron() {
         global $CFG, $DB;
+        require_once($CFG->libdir.'/cronlib.php');
 
         // find out all stale draft areas (older than 4 days) and purge them
         // those are identified by time stamp of the /. root dir