diff --git a/backup/tests/backup_cleanup_task_test.php b/backup/tests/backup_cleanup_task_test.php
index e4b71c8c9d5..98fdbb314fd 100644
--- a/backup/tests/backup_cleanup_task_test.php
+++ b/backup/tests/backup_cleanup_task_test.php
@@ -60,6 +60,7 @@ class core_backup_cleanup_task_testcase extends advanced_testcase {
             $user->id
         );
         $controller->execute_plan();
+        $controller->destroy(); // Unset all structures, close files...
         return $controller->get_backupid();
     }