diff --git a/src/emqttd.erl b/src/emqttd.erl
index 6b73d9027..763928b30 100644
--- a/src/emqttd.erl
+++ b/src/emqttd.erl
@@ -134,7 +134,7 @@ subscribers(Topic) ->
 subscriptions(Subscriber) ->
     with_pubsub(fun(PubSub) -> PubSub:subscriptions(Subscriber) end).
 
-with_pubsub(Fun) -> Fun(conf(pubsub_adapter)).
+with_pubsub(Fun) -> {ok, PubSub} = conf(pubsub_adapter), Fun(PubSub).
 
 dump() -> with_pubsub(fun(PubSub) -> lists:append(PubSub:dump(), zenmq_router:dump()) end).
 
diff --git a/src/emqttd_pubsub_sup.erl b/src/emqttd_pubsub_sup.erl
index 72d4fce68..5e26ed092 100644
--- a/src/emqttd_pubsub_sup.erl
+++ b/src/emqttd_pubsub_sup.erl
@@ -32,7 +32,7 @@ pubsub_pool() ->
     hd([Pid || {pubsub_pool, Pid, _, _} <- supervisor:which_children(?MODULE)]).
 
 init([Env]) ->
-    PubSub = emqttd:conf(pubsub_adapter),
+    {ok, PubSub} = emqttd:conf(pubsub_adapter),
     PubSubMFA = {PubSub, start_link, [Env]},
     PoolArgs = [pubsub, hash, pool_size(Env), PubSubMFA],
     PubSubPoolSup = emqttd_pool_sup:spec(pubsub_pool, PoolArgs),