diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index 76b495ea6c..b917643306 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -56,7 +56,8 @@ pref("extensions.systemAddon.update.enabled", true);
 
 // Disable add-ons that are not installed by the user in all scopes by default.
 // See the SCOPE constants in AddonManager.jsm for values to use here.
-pref("extensions.autoDisableScopes", 15);
+pref("extensions.autoDisableScopes", 0);
+pref("extensions.showMismatchUI", false);
 // Scopes to scan for changes at startup.
 pref("extensions.startupScanScopes", 0);