diff --git a/fcm.go b/fcm.go
index bb2459c..86c89ef 100644
--- a/fcm.go
+++ b/fcm.go
@@ -44,7 +44,10 @@ const (
 	maxMessages       = 500
 	multipartBoundary = "msg_boundary"
 
+	// Batch Send API
 	BatchSendEndpoint = "https://fcm.googleapis.com/batch"
+	// Requests to the endpoint will start failing after 6/21/2024.
+	// Migrate to the standard HTTP v1 API send method, which supports HTTP/2 for multiplexing.
 )
 
 var (