diff --git a/python/mach_bootstrap.py b/python/mach_bootstrap.py
index 557846f4896..56aa0143243 100644
--- a/python/mach_bootstrap.py
+++ b/python/mach_bootstrap.py
@@ -13,6 +13,12 @@ from distutils.spawn import find_executable
 from subprocess import Popen
 from tempfile import TemporaryFile
 
+SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
+TOP_DIR = os.path.abspath(os.path.join(SCRIPT_PATH, ".."))
+WPT_PATH = os.path.join(TOP_DIR, "tests", "wpt")
+WPT_RUNNER_PATH = os.path.join(WPT_PATH, "tests", "tools", "wptrunner")
+WPT_SERVE_PATH = os.path.join(WPT_PATH, "tests", "tools", "wptserve")
+
 SEARCH_PATHS = [
     os.path.join("python", "mach"),
 ]
@@ -125,30 +131,7 @@ def _process_exec(args):
                 sys.exit(1)
 
 
-def wpt_path(is_firefox, topdir, *paths):
-    if is_firefox:
-        rel = os.path.join("..", "testing", "web-platform")
-    else:
-        rel = os.path.join("tests", "wpt")
-
-    return os.path.join(topdir, rel, *paths)
-
-
-def wptrunner_path(is_firefox, topdir, *paths):
-    wpt_root = wpt_path(is_firefox, topdir)
-    rel = os.path.join(wpt_root, "tests", "tools", "wptrunner")
-
-    return os.path.join(topdir, rel, *paths)
-
-
-def wptserve_path(is_firefox, topdir, *paths):
-    wpt_root = wpt_path(is_firefox, topdir)
-    rel = os.path.join(wpt_root, "tests", "tools", "wptserve")
-
-    return os.path.join(topdir, rel, *paths)
-
-
-def _activate_virtualenv(topdir, is_firefox):
+def _activate_virtualenv(topdir):
     virtualenv_path = os.path.join(topdir, "python", "_virtualenv%d.%d" % (sys.version_info[0], sys.version_info[1]))
     python = sys.executable   # If there was no python, mach wouldn't have run at all!
     if not python:
@@ -184,8 +167,7 @@ def _activate_virtualenv(topdir, is_firefox):
     # and it will check for conflicts.
     requirements_paths = [
         os.path.join("python", "requirements.txt"),
-        wptrunner_path(is_firefox, topdir, "requirements.txt",),
-        wptrunner_path(is_firefox, topdir, "requirements_firefox.txt"),
+        os.path.join(WPT_RUNNER_PATH, "requirements.txt",),
     ]
 
     if need_pip_upgrade:
@@ -222,17 +204,10 @@ def _is_windows():
     return sys.platform == 'win32'
 
 
-def is_firefox_checkout(topdir):
-    parentdir = os.path.normpath(os.path.join(topdir, '..'))
-    is_firefox = os.path.isfile(os.path.join(parentdir,
-                                             'build/mach_bootstrap.py'))
-    return is_firefox
-
-
 def bootstrap_command_only(topdir):
     # we should activate the venv before importing servo.boostrap
     # because the module requires non-standard python packages
-    _activate_virtualenv(topdir, is_firefox_checkout(topdir))
+    _activate_virtualenv(topdir)
 
     # We cannot import these modules until the virtual environment
     # is active because they depend on modules installed via the
@@ -269,9 +244,7 @@ def bootstrap(topdir):
         print('You are running Python', platform.python_version())
         sys.exit(1)
 
-    is_firefox = is_firefox_checkout(topdir)
-
-    _activate_virtualenv(topdir, is_firefox)
+    _activate_virtualenv(topdir)
 
     def populate_context(context, key=None):
         if key is None:
@@ -281,10 +254,7 @@ def bootstrap(topdir):
         raise AttributeError(key)
 
     sys.path[0:0] = [os.path.join(topdir, path) for path in SEARCH_PATHS]
-
-    sys.path[0:0] = [wpt_path(is_firefox, topdir),
-                     wptrunner_path(is_firefox, topdir),
-                     wptserve_path(is_firefox, topdir)]
+    sys.path[0:0] = [WPT_PATH, WPT_RUNNER_PATH, WPT_SERVE_PATH]
 
     import mach.main
     mach = mach.main.Mach(os.getcwd())