diff --git a/src/emqx_metrics.erl b/src/emqx_metrics.erl
index fc04ab597..b363fd649 100644
--- a/src/emqx_metrics.erl
+++ b/src/emqx_metrics.erl
@@ -294,12 +294,12 @@ do_inc_recv(?PACKET(?DISCONNECT)) ->
 do_inc_recv(?PACKET(?AUTH)) ->
     inc('packets.auth.received');
 do_inc_recv(_Packet) ->
-    ignore.
+    ok.
 
 %% @doc Inc packets sent. Will not count $SYS PUBLISH.
--spec(inc_sent(emqx_mqtt_types:packet()) -> ok | ignore).
+-spec(inc_sent(emqx_mqtt_types:packet()) -> ok).
 inc_sent(?PUBLISH_PACKET(_QoS, <<"$SYS/", _/binary>>, _, _)) ->
-    ignore;
+    ok;
 inc_sent(Packet) ->
     inc('packets.sent'),
     do_inc_sent(Packet).
@@ -341,7 +341,7 @@ do_inc_sent(?PACKET(?DISCONNECT)) ->
 do_inc_sent(?PACKET(?AUTH)) ->
     inc('packets.auth.sent');
 do_inc_sent(_Packet) ->
-    ignore.
+    ok.
 
 %%------------------------------------------------------------------------------
 %% gen_server callbacks