diff --git a/webapp/controller/MissionController.class.php b/webapp/controller/MissionController.class.php
index 04d0a42a..69cd2d34 100644
--- a/webapp/controller/MissionController.class.php
+++ b/webapp/controller/MissionController.class.php
@@ -4,6 +4,7 @@ require_once('mt/Parameter.php');
 require_once('mt/Drop.php');
 require_once('mt/Task.php');
 require_once('mt/Season.php');
+require_once('mt/RankSeason.php');
 
 require_once('models/User.php');
 require_once('models/DynData.php');