diff --git a/src/wormhole_transit_relay/transit_server.py b/src/wormhole_transit_relay/transit_server.py
index 4b7b0b5..ad24d6c 100644
--- a/src/wormhole_transit_relay/transit_server.py
+++ b/src/wormhole_transit_relay/transit_server.py
@@ -47,6 +47,7 @@ class TransitConnection(LineReceiver):
         ITransitClient API
         """
         self._buddy = other
+        self._buddy._client.transport.registerProducer(self.transport, True)
 
     def disconnect_partner(self):
         """
@@ -198,6 +199,7 @@ class WebSocketTransitConnection(WebSocketServerProtocol):
         ITransitClient API
         """
         self._buddy = other
+        self._buddy._client.transport.registerProducer(self.transport, True)
 
     def disconnect_partner(self):
         """