diff --git a/apps/emqttd/src/emqttd_mnesia.erl b/apps/emqttd/src/emqttd_mnesia.erl
index 26dd0de42..7fbd084d4 100644
--- a/apps/emqttd/src/emqttd_mnesia.erl
+++ b/apps/emqttd/src/emqttd_mnesia.erl
@@ -40,7 +40,7 @@ init() ->
 
 %TODO: timeout should be configured?
 wait() ->
-    mnesia:wait_for_tables([topic, topic_trie, topic_trie_node, mqtt_user], 60000).
+    mnesia:wait_for_tables([topic, topic_trie, topic_trie_node], 30000).
 
 stop() ->
 	mnesia:stop().
diff --git a/apps/emqttd/src/x.erl b/apps/emqttd/src/x.erl
deleted file mode 100644
index 3993c1007..000000000
--- a/apps/emqttd/src/x.erl
+++ /dev/null
@@ -1,48 +0,0 @@
--module(x).
-
-%% ------------------------------------------------------------------
-%% API Function Exports
-%% ------------------------------------------------------------------
-
--export([start_link/0]).
-
-%% ------------------------------------------------------------------
-%% gen_server Function Exports
-%% ------------------------------------------------------------------
-
--export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
-
-%% ------------------------------------------------------------------
-%% API Function Definitions
-%% ------------------------------------------------------------------
-
-start_link() ->
-    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
-
-%% ------------------------------------------------------------------
-%% gen_server Function Definitions
-%% ------------------------------------------------------------------
-
-init(Args) ->
-    {ok, Args}.
-
-handle_call(_Request, _From, State) ->
-    {reply, ok, State}.
-
-handle_cast(_Msg, State) ->
-    {noreply, State}.
-
-handle_info(_Info, State) ->
-    {noreply, State}.
-
-terminate(_Reason, _State) ->
-    ok.
-
-code_change(_OldVsn, State, _Extra) ->
-    {ok, State}.
-
-%% ------------------------------------------------------------------
-%% Internal Function Definitions
-%% ------------------------------------------------------------------
-