diff --git a/apps/emqx_gateway/src/emqx_gateway_cm_registry.erl b/apps/emqx_gateway/src/emqx_gateway_cm_registry.erl
index e82537285..7cd45ef53 100644
--- a/apps/emqx_gateway/src/emqx_gateway_cm_registry.erl
+++ b/apps/emqx_gateway/src/emqx_gateway_cm_registry.erl
@@ -19,12 +19,8 @@
 
 -behaviour(gen_server).
 
-
 -export([start_link/1]).
 
-%% XXX: needless
-%-export([is_enabled/0]).
-
 -export([ register_channel/2
         , unregister_channel/2
         ]).
@@ -40,8 +36,7 @@
         , code_change/3
         ]).
 
--include_lib("emqx/include/emqx.hrl").
-
+-define(CM_SHARD, emqx_gateway_cm_shard).
 -define(LOCK, {?MODULE, cleanup_down}).
 
 -record(channel, {chid, pid}).
@@ -113,8 +108,7 @@ handle_info({membership, {mnesia, down, Node}}, State = #{type := Type}) ->
     Tab = tabname(Type),
     global:trans({?LOCK, self()},
                  fun() ->
-                     %% FIXME: The shard name should be fixed later
-                     mria:transaction(?MODULE, fun cleanup_channels/2, [Node, Tab])
+                     mria:transaction(?CM_SHARD, fun cleanup_channels/2, [Node, Tab])
                  end),
     {noreply, State};
 
diff --git a/apps/emqx_gateway/src/mqttsn/emqx_sn_registry.erl b/apps/emqx_gateway/src/mqttsn/emqx_sn_registry.erl
index 4f5734525..411a34aec 100644
--- a/apps/emqx_gateway/src/mqttsn/emqx_sn_registry.erl
+++ b/apps/emqx_gateway/src/mqttsn/emqx_sn_registry.erl
@@ -52,21 +52,6 @@
 
 -record(emqx_sn_registry, {key, value}).
 
-%% Mnesia bootstrap
-%-export([mnesia/1]).
-
-%-boot_mnesia({mnesia, [boot]}).
-
-%%% @doc Create or replicate tables.
-%-spec(mnesia(boot | copy) -> ok).
-%mnesia(boot) ->
-%    %% Optimize storage
-%    StoreProps = [{ets, [{read_concurrency, true}]}],
-%    ok = mria:create_table(?MODULE, [
-%            {attributes, record_info(fields, emqx_sn_registry)},
-%            {ram_copies, [node()]},
-%            {storage_properties, StoreProps}]).
-
 -type registry() :: {Tab :: atom(),
                      RegistryPid :: pid()}.
 
@@ -145,8 +130,6 @@ init([InstaId, PredefTopics]) ->
                 {rlog_shard, ?SN_SHARD}
                ]),
     ok = mria:wait_for_tables([Tab]),
-    % FIXME:
-    %ok = mria_rlog:wait_for_shards([?CM_SHARD], infinity),
     MaxPredefId = lists:foldl(
                     fun(#{id := TopicId, topic := TopicName0}, AccId) ->
                         TopicName = iolist_to_binary(TopicName0),