--- a/testing/marionette/harness/marionette_harness/tests/unit/test_date_time_value.py
+++ b/testing/marionette/harness/marionette_harness/tests/unit/test_date_time_value.py
@@ -6,26 +6,28 @@ from __future__ import absolute_import
 
 from datetime import datetime
 
 from marionette_driver.by import By
 from marionette_driver.date_time_value import DateTimeValue
 from marionette_harness import MarionetteTestCase
 
 
+def inline(doc):
+    return "data:text/html;charset=utf-8,{}".format(urllib.quote(doc))
+
+
 class TestDateTime(MarionetteTestCase):
     def test_set_date(self):
-        test_html = self.marionette.absolute_url("datetimePage.html")
-        self.marionette.navigate(test_html)
+        self.marionette.navigate(inline("<input id=\"date-test\" type=\"date\"/>")
 
         element = self.marionette.find_element(By.ID, "date-test")
         dt_value = DateTimeValue(element)
         dt_value.date = datetime(1998, 6, 2)
         self.assertEqual("1998-06-02", element.get_property("value"))
 
     def test_set_time(self):
-        test_html = self.marionette.absolute_url("datetimePage.html")
-        self.marionette.navigate(test_html)
+        self.marionette.navigate(inline("<input id=\"time-test\" type=\"time\"/>")
 
         element = self.marionette.find_element(By.ID, "time-test")
         dt_value = DateTimeValue(element)
         dt_value.time = datetime(1998, 11, 19, 9, 8, 7)
         self.assertEqual("09:08:07", element.get_property("value"))