diff --git a/app/Services/Dealer/OrderService.php b/app/Services/Dealer/OrderService.php
index e516a8cd..8c44bb7d 100644
--- a/app/Services/Dealer/OrderService.php
+++ b/app/Services/Dealer/OrderService.php
@@ -56,7 +56,7 @@ class OrderService
      * @param integer $number
      * @return string
      */
-    public function totalAmount(User $user, DealerProduct $product, int $number = 0, ?int $allNumber = 0)
+    public function totalAmount(User $user, DealerProduct $product, int $number = 0, ?int $allNumber = null)
     {
         return bcmul($this->getSalePrice($user, $product, $allNumber ?? $number), $number, 2);
     }