diff --git a/cmd/cart/cart-grain.go b/cmd/cart/cart-grain.go
index a05fdbe..326f8e4 100644
--- a/cmd/cart/cart-grain.go
+++ b/cmd/cart/cart-grain.go
@@ -262,7 +262,7 @@ func (c *CartGrain) UpdateTotals() {
 			value := NewPriceFromIncVat(voucher.Value, 25)
 
 			c.TotalDiscount.Add(*value)
-			c.TotalDiscount.Subtract(*value)
+			c.TotalPrice.Subtract(*value)
 		}
 	}
 }