diff --git a/firefox_ui_harness/default_prefs.py b/firefox_ui_harness/default_prefs.py
index 732a6463..ae4201a7 100644
--- a/firefox_ui_harness/default_prefs.py
+++ b/firefox_ui_harness/default_prefs.py
@@ -36,6 +36,7 @@
     'extensions.showMismatchUI': False,
     'extensions.update.enabled': False,
     'extensions.update.notifyUser': False,
+    'focusmanager.testmode': False,
     'geo.provider.testing': True,
     'javascript.options.showInConsole': True,
     'security.notification_enable_delay': 0,