diff --git a/apps/emqtt/include/emqtt_frame.hrl b/apps/emqtt/include/emqtt_frame.hrl
index e00191261..d51f3663b 100644
--- a/apps/emqtt/include/emqtt_frame.hrl
+++ b/apps/emqtt/include/emqtt_frame.hrl
@@ -18,6 +18,8 @@
 %% Copyright (c) 2007-2012 VMware, Inc.  All rights reserved.
 %%
 
+-define(CLIENT_ID_MAXLEN, 1024).
+
 -define(PROTOCOL_NAMES,  [{3, <<"MQIsdp">>}, {4, <<"MQTT">>}]).
 
 -define(MQTT_PROTO_MAJOR, 3).
diff --git a/apps/emqtt/src/emqtt_client.erl b/apps/emqtt/src/emqtt_client.erl
index daa322fa7..da5dabfb0 100644
--- a/apps/emqtt/src/emqtt_client.erl
+++ b/apps/emqtt/src/emqtt_client.erl
@@ -43,8 +43,6 @@
 
 -include("emqtt_frame.hrl").
 
--define(CLIENT_ID_MAXLEN, 23).
-
 -record(state, {socket,
 				conn_name,
 				await_recv,