diff --git a/src/emqx_packet.erl b/src/emqx_packet.erl
index 015f95e0d..8d90a3edc 100644
--- a/src/emqx_packet.erl
+++ b/src/emqx_packet.erl
@@ -429,7 +429,7 @@ format_variable(undefined, _) ->
 format_variable(Variable, undefined) ->
     format_variable(Variable);
 format_variable(Variable, Payload) ->
-    io_lib:format("~s, Payload=~0p", [format_variable(Variable), Payload]).
+    [format_variable(Variable), "Payload=", Payload].
 
 format_variable(#mqtt_packet_connect{
                  proto_ver    = ProtoVer,