diff --git a/src-server/Server/Communication/Handler.hs b/src-server/Server/Communication/Handler.hs
index e806841..7e1095f 100644
--- a/src-server/Server/Communication/Handler.hs
+++ b/src-server/Server/Communication/Handler.hs
@@ -67,8 +67,11 @@ handleMessage stateContainer readerContainer msg = do
           currentPlayers <- STM.atomically $ STM.readTMVar (scPlayers stateContainer)
           let newPlayers = filter (\p -> playerId p /= clientId) currentPlayers
           void $ STM.atomically $ STM.swapTMVar (scPlayers stateContainer) newPlayers
-          let client = find (\a -> csUUID a == Just clientId) socks
-          dropClient curLevel socketList queueList (csSocket $ fromJust client)
+          let mclient = find (\a -> csUUID a == Just clientId) socks
+          maybe
+            (logPrintIO curLevel Warning $ "unknown client: " <> show clientId)
+            (dropClient curLevel socketList queueList . csSocket)
+            mclient
           logPrintIO curLevel Info $ "client has quit the game: " <> show clientId
         ClientRequestWizard -> do
           let arena = rcMap readerContainer