diff --git a/webapp/services/MissionService.php b/webapp/services/MissionService.php
index 12775407..a6ef7185 100644
--- a/webapp/services/MissionService.php
+++ b/webapp/services/MissionService.php
@@ -114,7 +114,7 @@ class MissionService extends BaseService {
         if ($total > $target){
             $current = $current - ($total - $target);
             if ($current < 0){
-                $current = 0;
+                $current = -1;
             }
         }
         return $current;