diff --git a/testing/marionette/client/marionette_driver/geckoinstance.py b/testing/marionette/client/marionette_driver/geckoinstance.py
index bd88ae06be4b..e9d358d40a0b 100644
--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -37,7 +37,8 @@ class GeckoInstance(object):
         "extensions.autoDisableScopes": 10,
         "focusmanager.testmode": True,
         "marionette.defaultPrefs.enabled": True,
-        "startup.homepage_welcome_url": "about:blank",
+        "startup.homepage_welcome_url": "",
+        "startup.homepage_welcome_url.additional": "",
         "toolkit.telemetry.enabled": False,
         # Until Bug 1238095 is fixed, we have to enable CPOWs in order
         # for Marionette tests to work properly.
@@ -298,20 +299,22 @@ class DesktopInstance(GeckoInstance):
         'app.update.auto': False,
         'app.update.enabled': False,
         'browser.dom.window.dump.enabled': True,
+        'browser.firstrun-content.dismissed': True,
         # Bug 1145668 - Has to be reverted to about:blank once Marionette
         # can correctly handle error pages
         'browser.newtab.url': 'about:newtab',
         'browser.newtabpage.enabled': False,
         'browser.reader.detectedFirstArticle': True,
-        'browser.safebrowsing.phishing.enabled': False,
+        'browser.safebrowsing.blockedURIs.enabled': False,
         'browser.safebrowsing.forbiddenURIs.enabled': False,
         'browser.safebrowsing.malware.enabled': False,
-        'browser.safebrowsing.blockedURIs.enabled': False,
+        'browser.safebrowsing.phishing.enabled': False,
         'browser.search.update': False,
         'browser.tabs.animate': False,
         'browser.tabs.warnOnClose': False,
         'browser.tabs.warnOnOpen': False,
         'browser.uitour.enabled': False,
+        'browser.usedOnWindows10.introURL': '',
         'extensions.getAddons.cache.enabled': False,
         'extensions.installDistroAddons': False,
         'extensions.showMismatchUI': False,