diff --git a/cart-grain.go b/cart-grain.go
index 0454596..b6c512c 100644
--- a/cart-grain.go
+++ b/cart-grain.go
@@ -294,7 +294,7 @@ func (c *CartGrain) HandleMessage(message *Message, isReplay bool) (*FrameWithPa
 			for i, item := range c.Items {
 				if item.Id == int(msg.Id) {
 					if msg.Quantity <= 0 {
-						c.TotalPrice -= item.Price * int64(msg.Quantity)
+						c.TotalPrice -= item.Price * int64(item.Quantity)
 						c.Items = append(c.Items[:i], c.Items[i+1:]...)
 					} else {
 						diff := int(msg.Quantity) - item.Quantity