diff --git a/src/wormhole/server/cli.py b/src/wormhole/server/cli.py
index 59dbd9a..9596dbd 100644
--- a/src/wormhole/server/cli.py
+++ b/src/wormhole/server/cli.py
@@ -1,4 +1,5 @@
 from __future__ import print_function
+import json
 import click
 from ..cli.cli import Config, _compose
 
@@ -19,6 +20,21 @@ def server(ctx): # this is the setuptools entrypoint for bin/wormhole-server
     # server commands don't use
     ctx.obj = Config()
 
+def _validate_websocket_protocol_options(ctx, param, value):
+    return list(_validate_websocket_protocol_option(option) for option in value)
+
+def _validate_websocket_protocol_option(option):
+    try:
+        key, value = option.split("=", 1)
+    except ValueError:
+        raise click.BadParameter("format options as OPTION=VALUE")
+
+    try:
+        value = json.loads(value)
+    except:
+        raise click.BadParameter("could not parse JSON value for {}".format(key))
+
+    return (key, value)
 
 LaunchArgs = _compose(
     click.option(
@@ -58,6 +74,11 @@ LaunchArgs = _compose(
         "--stats-json-path", default="stats.json", metavar="PATH",
         help="location to write the relay stats file",
     ),
+    click.option(
+        "--websocket-protocol-option", multiple=True, metavar="OPTION=VALUE",
+        callback=_validate_websocket_protocol_options,
+        help="a websocket server protocol option to configure",
+    ),
 )
 
 
diff --git a/src/wormhole/test/test_cli.py b/src/wormhole/test/test_cli.py
index ba532bb..8e9d5bb 100644
--- a/src/wormhole/test/test_cli.py
+++ b/src/wormhole/test/test_cli.py
@@ -1238,3 +1238,45 @@ class Server(unittest.TestCase):
         relay = plugin.makeService(None)
         self.assertEqual('relay.sqlite', relay._db_url)
         self.assertEqual('stats.json', relay._stats_file)
+
+    @mock.patch("wormhole.server.cmd_server.start_server")
+    def test_websocket_protocol_options(self, fake_start_server):
+        result = self.runner.invoke(
+            server, [
+                'start',
+                '--websocket-protocol-option=a=3',
+                '--websocket-protocol-option=b=true',
+                '--websocket-protocol-option=c=3.5',
+                '--websocket-protocol-option=d=["foo","bar"]',
+            ])
+        self.assertEqual(0, result.exit_code)
+        cfg = fake_start_server.mock_calls[0][1][0]
+        self.assertEqual(
+            cfg.websocket_protocol_option,
+            [("a", 3), ("b", True), ("c", 3.5), ("d", ['foo', 'bar'])],
+        )
+
+    def test_broken_websocket_protocol_options(self):
+        result = self.runner.invoke(
+            server, [
+                'start',
+                '--websocket-protocol-option=a',
+            ])
+        self.assertNotEqual(0, result.exit_code)
+        self.assertIn(
+            'Error: Invalid value for "--websocket-protocol-option": '
+            'format options as OPTION=VALUE',
+            result.output,
+        )
+
+        result = self.runner.invoke(
+            server, [
+                'start',
+                '--websocket-protocol-option=a=foo',
+            ])
+        self.assertNotEqual(0, result.exit_code)
+        self.assertIn(
+            'Error: Invalid value for "--websocket-protocol-option": '
+            'could not parse JSON value for a',
+            result.output,
+        )