diff --git a/message.go b/message.go
index 17cdeb1..c8a0258 100644
--- a/message.go
+++ b/message.go
@@ -177,7 +177,7 @@ type ApnsPayload struct {
 
 	// TODO: add support for custom keys
 	// https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/generating_a_remote_notification
-	customKeys map[string]interface{}
+	customKeys map[string]any
 }
 
 type ApnsPayloadKeys struct {