diff --git a/src/emqttd_session.erl b/src/emqttd_session.erl
index 930454667..4a8a35933 100644
--- a/src/emqttd_session.erl
+++ b/src/emqttd_session.erl
@@ -354,13 +354,12 @@ handle_cast({resume, ClientId, ClientPid}, Session) ->
     %% Dequeue pending messages
     noreply(dequeue(Session2));
 
-%% PUBRAC
-handle_cast({puback, PktId}, Session = #session{client_id = ClientId, awaiting_ack = Awaiting}) ->
-    case maps:find(PktId, Awaiting) of
+%% PUBACK
+handle_cast({puback, PktId}, Session = #session{client_id = ClientId, awaiting_ack = AwaitingAck}) ->
+    case maps:find(PktId, AwaitingAck) of
         {ok, {_, TRef}} ->
             cancel_timer(TRef),
-            Session1 = acked(PktId, Session),
-            noreply(dequeue(Session1));
+            noreply(dequeue(acked(PktId, Session)));
         error ->
             lager:error("Session ~s cannot find PUBACK '~p'!", [ClientId, PktId]),
             noreply(Session)
@@ -375,7 +374,8 @@ handle_cast({pubrec, PktId}, Session = #session{client_id = ClientId,
         {ok, {_, TRef}} ->
             cancel_timer(TRef),
             TRef1 = timer(Timeout, {timeout, awaiting_comp, PktId}),
-            Session1 = acked(PktId, Session#session{awaiting_comp = maps:put(PktId, TRef1, AwaitingComp)}),
+            AwaitingComp1 = maps:put(PktId, TRef1, AwaitingComp),
+            Session1 = acked(PktId, Session#session{awaiting_comp = AwaitingComp1}),
             noreply(dequeue(Session1));
         error ->
             lager:error("Session ~s cannot find PUBREC '~p'!", [ClientId, PktId]),
@@ -439,9 +439,9 @@ handle_info({timeout, awaiting_ack, PktId}, Session = #session{client_pid = unde
     %% just remove awaiting
     noreply(Session#session{awaiting_ack = maps:remove(PktId, AwaitingAck)});
 
-handle_info({timeout, awaiting_ack, PktId}, Session = #session{client_id = ClientId,
+handle_info({timeout, awaiting_ack, PktId}, Session = #session{client_id      = ClientId,
                                                                inflight_queue = InflightQ,
-                                                               awaiting_ack = AwaitingAck}) ->
+                                                               awaiting_ack   = AwaitingAck}) ->
     case maps:find(PktId, AwaitingAck) of
         {ok, {{0, _Timeout}, _TRef}} ->
             Session1 = Session#session{inflight_queue = lists:keydelete(PktId, 1, InflightQ),
@@ -564,10 +564,11 @@ dequeue(Session) ->
 
 dequeue2(Session = #session{message_queue = Q}) ->
     case emqttd_mqueue:out(Q) of
-        {empty, _Q} -> Session;
+        {empty, _Q} ->
+            Session;
         {{value, Msg}, Q1} ->
-            Session1 = deliver(Msg, Session#session{message_queue = Q1}),
-            dequeue(Session1) %% dequeue more
+            %% dequeue more
+            dequeue(deliver(Msg, Session#session{message_queue = Q1}))
     end.
 
 deliver(Msg = #mqtt_message{qos = ?QOS_0}, Session = #session{client_pid = ClientPid}) ->
@@ -608,8 +609,8 @@ acked(PktId, Session = #session{client_id      = ClientId,
         false ->
             lager:error("Session(~s) cannot find acked message: ~p", [PktId])
     end,
-    Session#session{inflight_queue = lists:keydelete(PktId, 1, InflightQ),
-                    awaiting_ack   = maps:remove(PktId, Awaiting)}.
+    Session#session{awaiting_ack   = maps:remove(PktId, Awaiting),
+                    inflight_queue = lists:keydelete(PktId, 1, InflightQ)}.
 
 next_packet_id(Session = #session{packet_id = 16#ffff}) ->
     Session#session{packet_id = 1};
@@ -627,3 +628,4 @@ cancel_timer(Ref) ->
 
 noreply(State) ->
     {noreply, State, hibernate}.
+