diff --git a/apps/emqx/src/emqx_persistent_session_ds/shared_subs_agent.hrl b/apps/emqx/src/emqx_persistent_session_ds/shared_subs_agent.hrl
index 61681d752..4fcd43e8a 100644
--- a/apps/emqx/src/emqx_persistent_session_ds/shared_subs_agent.hrl
+++ b/apps/emqx/src/emqx_persistent_session_ds/shared_subs_agent.hrl
@@ -12,28 +12,33 @@
 %% agent from BSL app
 
 -ifdef(TEST).
+
 -define(shared_subs_agent, emqx_ds_shared_sub_agent).
+
+%% clause of -ifdef(TEST).
 -else.
+
 %% Till full implementation we need to dispach to the null agent.
 %% It will report "not implemented" error for attempts to use shared subscriptions.
 -define(shared_subs_agent, emqx_persistent_session_ds_shared_subs_null_agent).
-%% -ifdef(TEST).
+
+%% end of -ifdef(TEST).
 -endif.
 
-%% -if(?EMQX_RELEASE_EDITION == ee).
+%% clause of -if(?EMQX_RELEASE_EDITION == ee).
 -else.
 
 -define(shared_subs_agent, emqx_persistent_session_ds_shared_subs_null_agent).
 
-%% -if(?EMQX_RELEASE_EDITION == ee).
+%% end of -if(?EMQX_RELEASE_EDITION == ee).
 -endif.
 
-%% -ifdef(EMQX_RELEASE_EDITION).
+%% clause of -ifdef(EMQX_RELEASE_EDITION).
 -else.
 
 -define(shared_subs_agent, emqx_persistent_session_ds_shared_subs_null_agent).
 
-%% -ifdef(EMQX_RELEASE_EDITION).
+%% end of -ifdef(EMQX_RELEASE_EDITION).
 -endif.
 
 -endif.