diff --git a/du5/a_station.c b/du5/a_station.c
index 0b12508..4f0a7b1 100644
--- a/du5/a_station.c
+++ b/du5/a_station.c
@@ -52,7 +52,8 @@ void add_target_capacity(struct station* station,const char* target, int capacit
         return;
     }
    }
-   ptr->capacity += capacity;
+   int new_cap = ptr->capacity + capacity;
+   ptr->capacity = new_cap;
    return;