--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/executors/executormarionette.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/executors/executormarionette.py
@@ -57,17 +57,17 @@ class MarionetteProtocol(Protocol):
         """Connect to browser via Marionette."""
         Protocol.setup(self, runner)
 
         self.logger.debug("Connecting to Marionette on port %i" % self.marionette_port)
         startup_timeout = marionette.Marionette.DEFAULT_STARTUP_TIMEOUT * self.timeout_multiplier
         self.marionette = marionette.Marionette(host='localhost',
                                                 port=self.marionette_port,
                                                 socket_timeout=None,
-                                                startup_timeout=None)
+                                                startup_timeout=startup_timeout)
 
         try:
             self.logger.debug("Waiting for Marionette connection")
             while True:
                 try:
                     self.marionette.raise_for_port()
                     break
                 except IOError: