diff --git a/example/lib/src/rtm_api_demo.dart b/example/lib/src/rtm_api_demo.dart
index 42e746d..ace29f7 100644
--- a/example/lib/src/rtm_api_demo.dart
+++ b/example/lib/src/rtm_api_demo.dart
@@ -1,5 +1,6 @@
 import 'dart:collection';
 import 'dart:convert';
+import 'dart:typed_data';
 
 import 'package:agora_rtm/agora_rtm.dart';
 import 'package:flutter/material.dart';
@@ -372,7 +373,8 @@ class _RtmApiDemoState extends State<RtmApiDemo> {
                 _button('RtmClient.publishBinaryMessage', () async {
                   final result = await _rtmClient.publishBinaryMessage(
                       _channelNameController.text,
-                      utf8.encode(_rtmClientMessageController.text),
+                      Uint8List.fromList(
+                          utf8.encode(_rtmClientMessageController.text)),
                       channelType: _rtmChannelType,
                       messageType: RtmMessageType.rtmMessageTypeBinary,
                       customType: _rtmClientPublishCustomTypeController.text);