diff --git a/cmd/cart/cart-grain.go b/cmd/cart/cart-grain.go
index 326f8e4..3448274 100644
--- a/cmd/cart/cart-grain.go
+++ b/cmd/cart/cart-grain.go
@@ -260,6 +260,10 @@ func (c *CartGrain) UpdateTotals() {
 	for _, voucher := range c.Vouchers {
 		if _, ok := voucher.AppliesTo(c); ok {
 			value := NewPriceFromIncVat(voucher.Value, 25)
+			if c.TotalPrice.IncVat <= value.IncVat {
+				// don't apply discounts to more than the total price
+				continue
+			}
 
 			c.TotalDiscount.Add(*value)
 			c.TotalPrice.Subtract(*value)
diff --git a/pkg/voucher/service.go b/pkg/voucher/service.go
index fb14ef4..d75877e 100644
--- a/pkg/voucher/service.go
+++ b/pkg/voucher/service.go
@@ -21,7 +21,6 @@ type Voucher struct {
 
 type Service struct {
 	// Add fields here
-
 }
 
 var ErrInvalidCode = errors.New("invalid vouchercode")