diff --git a/composer/app/profile/all.js b/composer/app/profile/all.js
index f2c3e97d755..8866cffb27b 100644
--- a/composer/app/profile/all.js
+++ b/composer/app/profile/all.js
@@ -453,7 +453,7 @@ pref("dom.disable_window_open_feature.status",      false);
 
 pref("dom.allow_scripts_to_close_windows",          false);
 
-pref("javascript.enabled",                  true);
+pref("javascript.enabled",                  false);
 pref("javascript.allow.mailnews",           false);
 pref("javascript.options.strict",           false);
 pref("javascript.options.showInConsole",    true);