diff --git a/muxplex/main.py b/muxplex/main.py
index 7c2b51e..8b5cecf 100644
--- a/muxplex/main.py
+++ b/muxplex/main.py
@@ -17,6 +17,7 @@ import os
 import pathlib
 import pwd
 import socket
+import ssl
 import subprocess
 import sys
 import time
@@ -754,13 +755,27 @@ async def federation_terminal_ws_proxy(websocket: WebSocket, remote_id: int) ->
     else:
         ws_url = remote_url + "/terminal/ws"  # assume already ws:// or wss://
 
+    # Build an SSL context that skips verification for self-signed certs on
+    # remote instances.  Same rationale as httpx verify=False: federation
+    # peers may use self-signed or Tailscale-issued certs that don't pass the
+    # system CA store.  None tells websockets to use default behaviour (no
+    # TLS) for plain ws:// URLs.
+    ssl_context: ssl.SSLContext | None = None
+    if ws_url.startswith("wss://"):
+        ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
+        ssl_context.check_hostname = False
+        ssl_context.verify_mode = ssl.CERT_NONE
+
     await websocket.accept(subprotocol="tty")
 
     try:
         async with websockets.connect(
             ws_url,
             subprotocols=[Subprotocol("tty")],
-            additional_headers={"Authorization": f"Bearer {remote_key}"} if remote_key else {},
+            additional_headers={"Authorization": f"Bearer {remote_key}"}
+            if remote_key
+            else {},
+            ssl=ssl_context,
         ) as remote_ws:
 
             async def client_to_remote() -> None:
diff --git a/muxplex/tests/test_ws_proxy.py b/muxplex/tests/test_ws_proxy.py
index 4fb814b..5749a1e 100644
--- a/muxplex/tests/test_ws_proxy.py
+++ b/muxplex/tests/test_ws_proxy.py
@@ -442,3 +442,20 @@ def test_federation_ws_proxy_route_exists():
     assert "/federation/{remote_id}/terminal/ws" in paths, (
         "App must have a WebSocket route at /federation/{remote_id}/terminal/ws"
     )
+
+
+def test_federation_ws_proxy_uses_ssl_context_for_wss():
+    """Federation WS proxy must pass an SSL context when connecting via wss://.
+
+    Self-signed certs on remote instances (cortex, spark-2, etc.) fail the
+    default SSL verification in websockets.connect().  The proxy must build an
+    SSLContext with CERT_NONE for wss:// URLs — the same fix already applied
+    to the httpx client (verify=False) but for the websockets library.
+    """
+    from muxplex.main import federation_terminal_ws_proxy
+
+    source = inspect.getsource(federation_terminal_ws_proxy)
+    assert "ssl" in source and ("CERT_NONE" in source or "ssl_context" in source), (
+        "Federation WS proxy must configure an SSL context (CERT_NONE / ssl_context) "
+        "for self-signed cert support on wss:// connections"
+    )