--- a/mobile/android/app/mobile.js
+++ b/mobile/android/app/mobile.js
@@ -231,16 +231,18 @@ pref("extensions.compatability.locales.b
 pref("extensions.installDistroAddons", false);
 
 pref("extensions.webextPermissionPrompts", true);
 
 // Add-on content security policies.
 pref("extensions.webextensions.base-content-security-policy", "script-src 'self' https://* moz-extension: blob: filesystem: 'unsafe-eval' 'unsafe-inline'; object-src 'self' https://* moz-extension: blob: filesystem:;");
 pref("extensions.webextensions.default-content-security-policy", "script-src 'self'; object-src 'self';");
 
+pref("extensions.legacy.enabled", false);
+
 /* block popups by default, and notify the user about blocked popups */
 pref("dom.disable_open_during_load", true);
 pref("privacy.popups.showBrowserMessage", true);
 
 /* disable opening windows with the dialog feature */
 pref("dom.disable_window_open_dialog_feature", true);
 pref("dom.disable_window_showModalDialog", true);
 pref("dom.disable_window_print", true);