diff --git a/pytest_jupyter/jupyter_server.py b/pytest_jupyter/jupyter_server.py
index 1c84fe4..be9bd26 100644
--- a/pytest_jupyter/jupyter_server.py
+++ b/pytest_jupyter/jupyter_server.py
@@ -4,6 +4,7 @@
 from __future__ import annotations
 
 import importlib
+import inspect
 import io
 import logging
 import os
@@ -328,6 +329,10 @@ def client_fetch(*parts, headers=None, params=None, **kwargs):
             headers.setdefault(key, value)
         # Make request.
         req = tornado.httpclient.HTTPRequest(url, headers=headers, connect_timeout=120)
+        allowed = list(inspect.signature(tornado.websocket.websocket_connect).parameters)
+        for name in list(kwargs):
+            if name not in allowed:
+                del kwargs[name]
         return tornado.websocket.websocket_connect(req, **kwargs)
 
     return client_fetch