diff --git a/src/wormhole/server/rendezvous.py b/src/wormhole/server/rendezvous.py
index 122f780..3401008 100644
--- a/src/wormhole/server/rendezvous.py
+++ b/src/wormhole/server/rendezvous.py
@@ -24,9 +24,9 @@ class Channel:
         self._log_requests = log_requests
         self._appid = appid
         self._channelid = channelid
-        self._listeners = set() # instances with .send_rendezvous_event (that
-                                # takes a JSONable object) and
-                                # .stop_rendezvous_watcher()
+        self._listeners = {} # handle -> (send_f, stop_f)
+        # "handle" is a hashable object, for deregistration
+        # send_f() takes a JSONable object, stop_f() has no args
 
     def get_channelid(self):
         return self._channelid
@@ -44,17 +44,17 @@ class Channel:
                              "server_rx": row["server_rx"], "id": row["msgid"]})
         return messages
 
-    def add_listener(self, ep):
-        self._listeners.add(ep)
+    def add_listener(self, handle, send_f, stop_f):
+        self._listeners[handle] = (send_f, stop_f)
         return self.get_messages()
 
-    def remove_listener(self, ep):
-        self._listeners.discard(ep)
+    def remove_listener(self, handle):
+        self._listeners.pop(handle)
 
     def broadcast_message(self, phase, body, server_rx, msgid):
-        for ep in self._listeners:
-            ep.send_rendezvous_event({"phase": phase, "body": body,
-                                      "server_rx": server_rx, "id": msgid})
+        for (send_f, stop_f) in self._listeners.values():
+            send_f({"phase": phase, "body": body,
+                    "server_rx": server_rx, "id": msgid})
 
     def _add_message(self, side, phase, body, server_rx, msgid):
         db = self._db
@@ -183,15 +183,15 @@ class Channel:
 
         # Shut down any listeners, just in case they're still lingering
         # around.
-        for ep in self._listeners:
-            ep.stop_rendezvous_watcher()
+        for (send_f, stop_f) in self._listeners.values():
+            stop_f()
 
         self._app.free_channel(self._channelid)
 
     def _shutdown(self):
         # used at test shutdown to accelerate client disconnects
-        for ep in self._listeners:
-            ep.stop_rendezvous_watcher()
+        for (send_f, stop_f) in self._listeners.values():
+            stop_f()
 
 class AppNamespace:
     def __init__(self, db, welcome, blur_usage, log_requests, appid):
diff --git a/src/wormhole/server/rendezvous_websocket.py b/src/wormhole/server/rendezvous_websocket.py
index 93abf2c..6bd291b 100644
--- a/src/wormhole/server/rendezvous_websocket.py
+++ b/src/wormhole/server/rendezvous_websocket.py
@@ -150,8 +150,12 @@ class WebSocketRendezvous(websocket.WebSocketServerProtocol):
         if self._watching:
             raise Error("already watching")
         self._watching = True
-        for old_message in channel.add_listener(self):
-            self.send_rendezvous_event(old_message)
+        def _send(event):
+            self.send_rendezvous_event(event)
+        def _stop():
+            self.stop_rendezvous_watcher()
+        for old_message in channel.add_listener(self, _send, _stop):
+            _send(old_message)
 
     def handle_add(self, channel, msg, server_rx):
         if "phase" not in msg: