diff --git a/src/emqx_packet.erl b/src/emqx_packet.erl
index 715526964..c3eab87e1 100644
--- a/src/emqx_packet.erl
+++ b/src/emqx_packet.erl
@@ -69,9 +69,9 @@ validate_packet_id(0) ->
 validate_packet_id(_) ->
     true.
 
-validate_properties(?SUBSCRIBE, #{'Subscription-Identifier' := I})
-    when I =< 0; I >= 16#FFFFFFF ->
-    error(subscription_identifier_invalid);
+validate_properties(?SUBSCRIBE, #{'Subscription-Identifier' := _I}) ->
+    %% when I =< 0; I >= 16#FFFFFFF ->
+    error(protocol_error);
 validate_properties(?PUBLISH, # {'Topic-Alias':= I})
     when I =:= 0 ->
     error(topic_alias_invalid);
@@ -236,4 +236,3 @@ format_password(_Password) -> '******'.
 i(true)  -> 1;
 i(false) -> 0;
 i(I) when is_integer(I) -> I.
-