diff --git a/src/Simplex/Messaging/Server.hs b/src/Simplex/Messaging/Server.hs
index 278f4ba3e..29856098d 100644
--- a/src/Simplex/Messaging/Server.hs
+++ b/src/Simplex/Messaging/Server.hs
@@ -277,17 +277,17 @@ smpServer started cfg@ServerConfig {transports, transportConfig = tCfg, startOpt
           Nothing -> updateSubDisconnected
           where
             updateSubConnected c = case clntSub of
-              CSClient qId prevServiceId serviceId_ -> do
+              CSClient qId k prevServiceId serviceId_ -> do
                 modifyTVar' subClients $ IS.insert clntId -- add ID to server's subscribed cients
                 as'' <- if prevServiceId == serviceId_ then pure [] else endServiceSub prevServiceId qId END
                 case serviceId_ of
                   Just serviceId -> do
                     modifyTVar' totalServiceSubs $ addServiceSubs (1, queueIdHash qId) -- server count and IDs hash for all services
                     as <- endQueueSub qId END
-                    as' <- cancelServiceSubs serviceId =<< upsertSubscribedClient serviceId c serviceSubscribers
+                    as' <- cancelServiceSubs serviceId =<< upsertSubscribedClient (subKey serviceId) c serviceSubscribers
                     pure $ as ++ as' ++ as''
                   Nothing -> do
-                    as <- prevSub qId END (CSAEndSub qId) =<< upsertSubscribedClient qId c queueSubscribers
+                    as <- prevSub qId END (CSAEndSub qId) =<< upsertSubscribedClient k c queueSubscribers
                     pure $ as ++ as''
               CSDeleted qId serviceId -> do
                 removeWhenNoSubs c
@@ -297,10 +297,10 @@ smpServer started cfg@ServerConfig {transports, transportConfig = tCfg, startOpt
               CSService serviceId changedSubs -> do
                 modifyTVar' subClients $ IS.insert clntId -- add ID to server's subscribed cients
                 modifyTVar' totalServiceSubs $ addServiceSubs changedSubs -- server count and IDs hash for all services
-                cancelServiceSubs serviceId =<< upsertSubscribedClient serviceId c serviceSubscribers
+                cancelServiceSubs serviceId =<< upsertSubscribedClient (subKey serviceId) c serviceSubscribers
             updateSubDisconnected = case clntSub of
                 -- do not insert client if it is already disconnected, but send END/DELD to any other client subscribed to this queue or service
-                CSClient qId prevServiceId serviceId -> do
+                CSClient qId _ prevServiceId serviceId -> do
                   as <- endQueueSub qId END
                   as' <- endServiceSub serviceId qId END
                   as'' <- if prevServiceId == serviceId then pure [] else endServiceSub prevServiceId qId END
@@ -1720,12 +1720,13 @@ client
 
         subscribeNewQueue :: RecipientId -> QueueRec -> M s ()
         subscribeNewQueue rId QueueRec {rcvServiceId} = do
+          let k = subKey rId
           case rcvServiceId of
             Just _ -> atomically $ modifyTVar' (serviceSubsCount clnt) $ addServiceSubs (1, queueIdHash rId)
             Nothing -> do
               sub <- atomically $ newSubscription NoSub
-              atomically $ TM.insert (subKey rId) sub $ subscriptions clnt
-          atomically $ writeTQueue (subQ subscribers) (CSClient rId rcvServiceId rcvServiceId, clientId)
+              atomically $ TM.insert k sub $ subscriptions clnt
+          atomically $ writeTQueue (subQ subscribers) (CSClient rId k rcvServiceId rcvServiceId, clientId)
 
         -- clients that use GET are not added to server subscribers
         getMessage :: StoreQueue s -> QueueRec -> M s (Transmission BrokerMsg)
@@ -1804,7 +1805,8 @@ client
         sharedSubscribeQueue q queueServiceId srvSubscribers clientSubs clientServiceSubs mkSub servicesSel = do
           stats <- asks serverStats
           let incSrvStat sel = incStat $ sel $ servicesSel stats
-              writeSub = writeTQueue (subQ srvSubscribers) (CSClient entId queueServiceId clntServiceId, clientId)
+              k = subKey entId
+              writeSub = writeTQueue (subQ srvSubscribers) (CSClient entId k queueServiceId clntServiceId, clientId)
           liftIO $ case clntServiceId of
             Just serviceId
               | queueServiceId == Just serviceId -> do
@@ -1842,12 +1844,12 @@ client
                 unless hasSub $ atomically writeSub
                 pure r
               where
-                getSubscription = TM.lookup (subKey entId) $ clientSubs clnt
+                getSubscription = TM.lookup k $ clientSubs clnt
                 newSub = \case
                   Just sub -> pure (True, Just sub)
                   Nothing -> do
                     sub <- mkSub
-                    TM.insert (subKey entId) sub $ clientSubs clnt
+                    TM.insert k sub $ clientSubs clnt
                     pure (False, Just sub)
 
         subscribeServiceMessages :: ServiceId -> (Int64, IdsHash) -> M s BrokerMsg
diff --git a/src/Simplex/Messaging/Server/Env/STM.hs b/src/Simplex/Messaging/Server/Env/STM.hs
index 732b9f881..414352f7d 100644
--- a/src/Simplex/Messaging/Server/Env/STM.hs
+++ b/src/Simplex/Messaging/Server/Env/STM.hs
@@ -410,16 +410,14 @@ getSubscribedClient entId (SubscribedClients cs) = TM.lookupIO (subKey entId) cs
 {-# INLINE getSubscribedClient #-}
 
 -- insert subscribed and current client, return previously subscribed client if it is different
-upsertSubscribedClient :: EntityId -> Client s -> SubscribedClients s -> STM (Maybe (Client s))
-upsertSubscribedClient entId c (SubscribedClients cs) =
+upsertSubscribedClient :: SubKey -> Client s -> SubscribedClients s -> STM (Maybe (Client s))
+upsertSubscribedClient k c (SubscribedClients cs) =
   TM.lookup k cs >>= \case
     Nothing -> Nothing <$ TM.insertM k (newTVar (Just c)) cs
     Just cv ->
       readTVar cv >>= \case
         Just c' | sameClientId c c' -> pure Nothing
         c_ -> c_ <$ writeTVar cv (Just c)
-  where
-    k = subKey entId
 
 lookupSubscribedClient :: EntityId -> SubscribedClients s -> STM (Maybe (Client s))
 lookupSubscribedClient entId (SubscribedClients cs) = TM.lookup (subKey entId) cs $>>= readTVar
@@ -451,7 +449,7 @@ sameClient c cv = maybe False (sameClientId c) <$> readTVar cv
 {-# INLINE sameClient #-}
 
 data ClientSub
-  = CSClient QueueId (Maybe ServiceId) (Maybe ServiceId) -- includes previous and new associated service IDs
+  = CSClient QueueId SubKey (Maybe ServiceId) (Maybe ServiceId) -- includes the key in client subscriptions, previous and new associated service IDs
   | CSDeleted QueueId (Maybe ServiceId) -- includes previously associated service IDs
   | CSService ServiceId (Int64, IdsHash) -- only send END to idividual client subs on message delivery, not of SSUB/NSSUB