diff --git a/appstore/model.go b/appstore/model.go
index 67f0072..138693b 100644
--- a/appstore/model.go
+++ b/appstore/model.go
@@ -17,7 +17,7 @@ type Environment string
 
 const (
 	Sandbox    Environment = "Sandbox"
-	Production Environment = "PROD"
+	Production Environment = "Production"
 )
 
 type (
diff --git a/appstore/notification.go b/appstore/notification.go
index 7463cc2..c584c77 100644
--- a/appstore/notification.go
+++ b/appstore/notification.go
@@ -16,6 +16,13 @@ const (
 	NotificationTypeDidChangeRenewalPreference NotificationType = "DID_CHANGE_RENEWAL_PREFERENCE"
 )
 
+type NotificationEnvironment string
+
+const (
+	NotificationSandbox    NotificationEnvironment = "Sandbox"
+	NotificationProduction NotificationEnvironment = "PROD"
+)
+
 type NotificationExpiresDate struct {
 	ExpiresDateMS  string `json:"expires_date"`
 	ExpiresDateUTC string `json:"expires_date_formatted"`
@@ -44,8 +51,8 @@ type NotificationReceipt struct {
 }
 
 type SubscriptionNotification struct {
-	Environment      Environment      `json:"environment"`
-	NotificationType NotificationType `json:"notification_type"`
+	Environment      NotificationEnvironment `json:"environment"`
+	NotificationType NotificationType        `json:"notification_type"`
 
 	// Not show in raw notify body
 	Password              string `json:"password"`