diff --git a/testing/web-platform/tests/tools/wpt/browser.py b/testing/web-platform/tests/tools/wpt/browser.py
index 01b7b2ad2267a..271e6f898a760 100644
--- a/testing/web-platform/tests/tools/wpt/browser.py
+++ b/testing/web-platform/tests/tools/wpt/browser.py
@@ -13,6 +13,8 @@
 from io import BytesIO
 
 from utils import call, get, untar, unzip
+from mozdownload import FactoryScraper
+import mozinstall
 
 logger = logging.getLogger(__name__)
 
@@ -105,36 +107,29 @@ def platform_string_geckodriver(self):
 
         return "%s%s" % (platform, bits)
 
-    def latest_nightly_listing(self):
-        resp = get("https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central/")
-        resp.raise_for_status()
-        return resp.text
-
-    def get_nightly_link(self, index, platform):
-        pattern = re.compile("<a[^>]*>(firefox-(\d+)\.\d(?:\w\d)?.en-US.%s\.tar\.bz2)" % platform)
-        max_version = None
-        for match in pattern.finditer(index):
-            try:
-                version = int(match.group(2))
-            except ValueError:
-                continue
-            if max_version is None or version > max_version[0]:
-                max_version = (version, match.group(1))
-        if not max_version:
-            raise ValueError("Failed to find version to download")
-        return ("https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central/%s" %
-                max_version[1])
-
     def install(self, dest=None):
         """Install Firefox."""
+
         if dest is None:
             dest = os.getcwd()
 
-        nightly_link = self.get_nightly_link(self.latest_nightly_listing(),
-                                             self.platform_string())
-        resp = get(nightly_link)
-        resp.raise_for_status()
-        untar(resp.raw, dest=dest)
+        filename = FactoryScraper('daily', branch='mozilla-central', destination=dest).download()
+
+        try:
+            mozinstall.install(filename, dest)
+        except mozinstall.mozinstall.InstallError as e:
+            if uname[0] == "Darwin":
+                # mozinstall will fail here if nightly is already installed in the venv
+                # This only occurs on macOS because shutil.copy_tree() is called in
+                # mozinstall._install_dmg and will fail if the file already exists.
+                # copytree isn't used while installing on Windows/linux, so the same error
+                # won't be thrown if we try to rewrite there.
+                mozinstall.uninstall(dest+'/Firefox Nightly.app')
+                mozinstall.install(filename, dest)
+            else:
+                raise
+
+        os.remove(filename)
         return find_executable("firefox", os.path.join(dest, "firefox"))
 
     def find_binary(self):
diff --git a/testing/web-platform/tests/tools/wpt/commands.json b/testing/web-platform/tests/tools/wpt/commands.json
index 38cdd3a368736..89669cafe0885 100644
--- a/testing/web-platform/tests/tools/wpt/commands.json
+++ b/testing/web-platform/tests/tools/wpt/commands.json
@@ -1,6 +1,6 @@
 {
     "run": {"path": "run.py", "script": "run", "parser": "create_parser", "help": "Run tests in a browser",
-            "virtualenv": true, "install": ["requests"], "requirements": ["../wptrunner/requirements.txt"]},
+            "virtualenv": true, "install": ["requests", "mozinstall", "mozdownload"], "requirements": ["../wptrunner/requirements.txt"]},
     "update-expectations": {"path": "update.py", "script": "update_expectations",
                             "parser": "create_parser_update", "help": "Update expectations files from raw logs.",
                             "virtualenv": true, "install": ["requests"],
diff --git a/testing/web-platform/tests/tools/wpt/tests/test_browser.py b/testing/web-platform/tests/tools/wpt/tests/test_browser.py
deleted file mode 100644
index 7a51a01fd7e6a..0000000000000
--- a/testing/web-platform/tests/tools/wpt/tests/test_browser.py
+++ /dev/null
@@ -1,13 +0,0 @@
-import os
-
-from tools.wpt import browser
-
-here = os.path.dirname(__file__)
-
-
-def test_firefox_nightly_link():
-    expected = ("https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central/"
-                "firefox-60.0a1.en-US.linux-x86_64.tar.bz2")
-    with open(os.path.join(here, "latest_mozilla_central.txt")) as index:
-        fx = browser.Firefox()
-        assert fx.get_nightly_link(index.read(), "linux-x86_64") == expected
diff --git a/testing/web-platform/tests/tools/wptrunner/requirements_firefox.txt b/testing/web-platform/tests/tools/wptrunner/requirements_firefox.txt
index 43413cf553983..782a6a09221ce 100644
--- a/testing/web-platform/tests/tools/wptrunner/requirements_firefox.txt
+++ b/testing/web-platform/tests/tools/wptrunner/requirements_firefox.txt
@@ -4,3 +4,5 @@ mozprocess == 0.26
 mozcrash == 1.0
 mozrunner == 6.14
 mozleak == 0.1
+mozinstall == 1.15
+mozdownload == 1.23