diff --git a/serversession-backend-persistent/src/Web/ServerSession/Backend/Persistent/Internal/Impl.hs b/serversession-backend-persistent/src/Web/ServerSession/Backend/Persistent/Internal/Impl.hs
index 4e75ce2..f328923 100644
--- a/serversession-backend-persistent/src/Web/ServerSession/Backend/Persistent/Internal/Impl.hs
+++ b/serversession-backend-persistent/src/Web/ServerSession/Backend/Persistent/Internal/Impl.hs
@@ -90,7 +90,7 @@ instance Storage SqlStorage where
       (void $ P.insert $ toPersistentSession session)
       (\old -> liftIO $ E.throwIO $ SessionAlreadyExists old session)
       mold
-  replaceSession s session = do
+  replaceSession _ session = do
     let key = psKey $ sessionKey session
     mold <- P.get key
     maybe