diff --git a/testing/firefox-ui/tests/puppeteer/test_about_window.py b/testing/firefox-ui/tests/puppeteer/test_about_window.py
index d37f3e1646a9..c8cf2036d413 100644
--- a/testing/firefox-ui/tests/puppeteer/test_about_window.py
+++ b/testing/firefox-ui/tests/puppeteer/test_about_window.py
@@ -53,10 +53,6 @@ class TestAboutWindow(PuppeteerMixin, MarionetteTestCase):
         # downloading panel
         self.assertEqual(self.deck.downloading.element.get_property('localName'), 'hbox')
 
-        # check deck attributes
-        self.assertIsInstance(self.deck.selected_index, int)
-        self.assertEqual(self.deck.selected_panel, self.deck.check_for_updates)
-
     def test_open_window(self):
         """Test various opening strategies."""
         def opener(win):
diff --git a/testing/firefox-ui/tests/puppeteer/test_update_wizard.py b/testing/firefox-ui/tests/puppeteer/test_update_wizard.py
index 5cdb6291a2df..af4f1c969c95 100644
--- a/testing/firefox-ui/tests/puppeteer/test_update_wizard.py
+++ b/testing/firefox-ui/tests/puppeteer/test_update_wizard.py
@@ -60,7 +60,3 @@ class TestUpdateWizard(PuppeteerMixin, MarionetteTestCase):
         # elements of the downloading panel
         self.assertEqual(self.wizard.downloading.progress.get_property('localName'),
                          'progressmeter')
-
-        # check wizard attributes
-        self.assertIsInstance(self.wizard.selected_index, int)
-        self.assertEqual(self.wizard.selected_panel, self.wizard.checking)
diff --git a/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/about_window/deck.py b/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/about_window/deck.py
index 9d8d90603c13..53c25355dad0 100644
--- a/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/about_window/deck.py
+++ b/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/about_window/deck.py
@@ -114,7 +114,7 @@ class Deck(UIBaseLib):
 
         :return: Index of the selected panel.
         """
-        return int(self.element.get_property('selectedIndex'))
+        return int(self.element.get_attribute('selectedIndex'))
 
     @property
     def selected_panel(self):
diff --git a/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/update_wizard/wizard.py b/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/update_wizard/wizard.py
index 9687ac917812..95ac9cad9bfb 100644
--- a/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/update_wizard/wizard.py
+++ b/testing/marionette/puppeteer/firefox/firefox_puppeteer/ui/update_wizard/wizard.py
@@ -207,7 +207,7 @@ class Wizard(UIBaseLib):
 
         :return: Index of the selected panel.
         """
-        return int(self.element.get_property('pageIndex'))
+        return int(self.element.get_attribute('pageIndex'))
 
     @property
     def selected_panel(self):