diff --git a/apps/emqx/test/emqx_persistent_session_SUITE.erl b/apps/emqx/test/emqx_persistent_session_SUITE.erl
index 7647f088f..54b759e87 100644
--- a/apps/emqx/test/emqx_persistent_session_SUITE.erl
+++ b/apps/emqx/test/emqx_persistent_session_SUITE.erl
@@ -265,33 +265,37 @@ snabbkaffe_sync_publish(Topic, Payloads) ->
                                     , #{?snk_kind := ps_persist_msg, payload := Payload}
                                     )
           end,
-    do_publish(Payloads, Fun).
+    do_publish(Payloads, Fun, true).
 
 publish(Topic, Payloads) ->
     Fun = fun(Client, Payload) ->
                   {ok, _} = emqtt:publish(Client, Topic, Payload, 2)
           end,
-    do_publish(Payloads, Fun).
+    do_publish(Payloads, Fun, false).
 
-do_publish(Payloads = [_|_], PublishFun) ->
+do_publish(Payloads = [_|_], PublishFun, WaitForUnregister) ->
     %% Publish from another process to avoid connection confusion.
     {Pid, Ref} =
         spawn_monitor(
           fun() ->
                   %% For convenience, always publish using tcp.
                   %% The publish path is not what we are testing.
+                  ClientID = <<"ps_SUITE_publisher">>,
                   {ok, Client} = emqtt:start_link([ {proto_ver, v5}
+                                                  , {clientid, ClientID}
                                                   , {port, 1883} ]),
                   {ok, _} = emqtt:connect(Client),
                   lists:foreach(fun(Payload) -> PublishFun(Client, Payload) end, Payloads),
-                  ok = emqtt:disconnect(Client)
+                  ok = emqtt:disconnect(Client),
+                  %% Snabbkaffe sometimes fails unless all processes are gone.
+                  [wait_for_cm_unregister(ClientID) || WaitForUnregister]
           end),
     receive
         {'DOWN', Ref, process, Pid, normal} -> ok;
         {'DOWN', Ref, process, Pid, What} -> error({failed_publish, What})
     end;
-do_publish(Payload, PublishFun) ->
-    do_publish([Payload], PublishFun).
+do_publish(Payload, PublishFun, WaitForUnregister) ->
+    do_publish([Payload], PublishFun, WaitForUnregister).
 
 %%--------------------------------------------------------------------
 %% Test Cases