diff --git a/webapp/controller/TankController.class.php b/webapp/controller/TankController.class.php
index ba646c4..4ebfea4 100644
--- a/webapp/controller/TankController.class.php
+++ b/webapp/controller/TankController.class.php
@@ -495,7 +495,7 @@ class TankController{
             'tank_id' => $tank_id,
             'tank_level' => $row['tank_level'] + 1,
             "fragment_id" => $row['fragment_id'],
-            "fragment_num" => $row['fragment_num'] - $coin_num,
+            "fragment_num" => $row['fragment_num'] - $fragment_num,
         ));
     }
 }