--- a/testing/firefox-ui/tests/puppeteer/test_utils.py
+++ b/testing/firefox-ui/tests/puppeteer/test_utils.py
@@ -8,17 +8,18 @@ from marionette_harness import Marionett
 
 class TestSanitize(PuppeteerMixin, MarionetteTestCase):
 
     def setUp(self):
         super(TestSanitize, self).setUp()
 
         # Clear all previous history and cookies.
         self.puppeteer.places.remove_all_history()
-        self.marionette.delete_all_cookies()
+        with self.marionette.using_context('content'):
+            self.marionette.delete_all_cookies()
 
         self.urls = [
             'layout/mozilla_projects.html',
             'layout/mozilla.html',
             'layout/mozilla_mission.html',
             'cookies/cookie_single.html'
         ]
         self.urls = [self.marionette.absolute_url(url) for url in self.urls]
@@ -33,11 +34,15 @@ class TestSanitize(PuppeteerMixin, Mario
     def test_sanitize_history(self):
         """ Clears history. """
         self.assertEqual(self.puppeteer.places.get_all_urls_in_history(), self.urls)
         self.puppeteer.utils.sanitize(data_type={"history": True})
         self.assertEqual(self.puppeteer.places.get_all_urls_in_history(), [])
 
     def test_sanitize_cookies(self):
         """ Clears cookies. """
-        self.assertIsNotNone(self.marionette.get_cookie('litmus_1'))
+        with self.marionette.using_context('content'):
+            self.assertIsNotNone(self.marionette.get_cookie('litmus_1'))
+
         self.puppeteer.utils.sanitize(data_type={"cookies": True})
-        self.assertIsNone(self.marionette.get_cookie('litmus_1'))
+
+        with self.marionette.using_context('content'):
+            self.assertIsNone(self.marionette.get_cookie('litmus_1'))