diff --git a/src/TXMLConnector/Internal.hs b/src/TXMLConnector/Internal.hs
index c8597eb..44757ef 100644
--- a/src/TXMLConnector/Internal.hs
+++ b/src/TXMLConnector/Internal.hs
@@ -349,7 +349,8 @@ handleTransaqData transaqData = do
             log Debug "TXMLConnector.WorkThread" $ "Sending order notification: " <> (T.pack . show) notif
             liftIO $ atomically $ do
               m <- readTVar (bsOrderTransactionIdMap brState)
-              when (BM.notMemberR (ExchangeOrderId (oOrderNo orderUpdate)) m) $ do
+              when (oOrderNo orderUpdate /= 0 &&
+                    BM.notMemberR (ExchangeOrderId (oOrderNo orderUpdate)) m) $ do
                 modifyTVar' (bsOrderTransactionIdMap brState) (BM.insert oid (ExchangeOrderId $ oOrderNo orderUpdate))
             liftIO $ cb notif
           _ -> log Warning "TXMLConnector.WorkThread" "Unable to find order for order notification"