diff --git a/electionpage/tests.py b/electionpage/tests.py
index 830c6a17..9243b042 100644
--- a/electionpage/tests.py
+++ b/electionpage/tests.py
@@ -118,8 +118,8 @@ def test_election_pages(self):
         self.assertEqual(bargraphButton.get_attribute('class'), 'btn btn-primary')
 
         # And the height was correctly set via PostMessages
-        self.assertEqual(bargraphIframeWrapper.find_element(
-            By.TAG_NAME, 'iframe').get_attribute('height'), '328px')
+        self._ensure_eventually_asserts(lambda: self.assertEqual(bargraphIframeWrapper.find_element(
+            By.TAG_NAME, 'iframe').get_attribute('height'), '328px'))
 
     @Mocker()
     def test_scrape_all(self, requestMock):