diff --git a/response.go b/response.go
index 99d6345..e760865 100644
--- a/response.go
+++ b/response.go
@@ -83,6 +83,9 @@ const (
 
 	// 405 The specified :method was not POST.
 	ReasonMethodNotAllowed = "MethodNotAllowed"
+	
+	/// 410 The device token has expired.
+	ReasonExpiredToken = "ExpiredToken"
 
 	// 410 The device token is inactive for the specified topic.
 	ReasonUnregistered = "Unregistered"