diff --git a/mod/subthread.php b/mod/subthread.php
index 29d3f5e06..0399ac0ce 100644
--- a/mod/subthread.php
+++ b/mod/subthread.php
@@ -6,6 +6,7 @@ use Friendica\App;
 use Friendica\Core\Hook;
 use Friendica\Core\L10n;
 use Friendica\Core\Logger;
+use Friendica\Core\Session;
 use Friendica\Core\System;
 use Friendica\Database\DBA;
 use Friendica\Model\Item;