diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
index 168a576c25a..8173d4f468f 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
@@ -38,6 +38,7 @@ def browser_kwargs(test_type, run_info_data, **kwargs):
     return {
         "binary": kwargs["binary"],
         "debug_info": kwargs["debug_info"],
+        "server_config": kwargs["config"],
         "user_stylesheets": kwargs.get("user_stylesheets"),
     }
 
@@ -73,14 +74,14 @@ class ServoWebDriverBrowser(Browser):
     used_ports = set()
 
     def __init__(self, logger, binary, debug_info=None, webdriver_host="127.0.0.1",
-                 user_stylesheets=None):
+                 server_config=None, user_stylesheets=None):
         Browser.__init__(self, logger)
         self.binary = binary
         self.webdriver_host = webdriver_host
         self.webdriver_port = None
         self.proc = None
         self.debug_info = debug_info
-        self.hosts_path = write_hosts_file()
+        self.hosts_path = write_hosts_file(server_config)
         self.command = None
         self.user_stylesheets = user_stylesheets if user_stylesheets else []
 
@@ -151,7 +152,7 @@ class ServoWebDriverBrowser(Browser):
 
     def cleanup(self):
         self.stop()
-        shutil.rmtree(os.path.dirname(self.hosts_file))
+        os.remove(self.hosts_path)
 
     def executor_browser(self):
         assert self.webdriver_port is not None
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
index f649a75cd93..581d3d7683d 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
@@ -11,8 +11,10 @@ from .base import (Protocol,
                    TestharnessExecutor,
                    strip_server)
 from ..testrunner import Stop
+from ..webdriver_server import wait_for_service
 
 webdriver = None
+ServoCommandExtensions = None
 
 here = os.path.join(os.path.split(__file__)[0])
 
@@ -23,6 +25,26 @@ def do_delayed_imports():
     global webdriver
     import webdriver
 
+    global ServoCommandExtensions
+    class ServoCommandExtensions(object):
+        def __init__(self, session):
+            self.session = session
+
+        @webdriver.client.command
+        def get_prefs(self, *prefs):
+            body = {"prefs": list(prefs)}
+            return self.session.send_command("POST", "servo/prefs/get", body)
+
+        @webdriver.client.command
+        def set_prefs(self, prefs):
+            body = {"prefs": prefs}
+            return self.session.send_command("POST", "servo/prefs/set", body)
+
+        @webdriver.client.command
+        def reset_prefs(self, *prefs):
+            body = {"prefs": list(prefs)}
+            return self.session.send_command("POST", "servo/prefs/reset", body)
+
 
 class ServoWebDriverProtocol(Protocol):
     def __init__(self, executor, browser, capabilities, **kwargs):
@@ -35,8 +57,7 @@ class ServoWebDriverProtocol(Protocol):
 
     def connect(self):
         """Connect to browser via WebDriver."""
-        self.session = webdriver.Session(self.host, self.port,
-                                         extension=webdriver.servo.ServoCommandExtensions)
+        self.session = webdriver.Session(self.host, self.port, extension=ServoCommandExtensions)
         self.session.start()
 
     def after_connect(self):