diff --git a/openerp/addons/base/res/res_lang.py b/openerp/addons/base/res/res_lang.py
index 92a8e0e8652..1325b544e52 100644
--- a/openerp/addons/base/res/res_lang.py
+++ b/openerp/addons/base/res/res_lang.py
@@ -181,6 +181,8 @@ class lang(osv.osv):
 
         if vals.get('active') == False:
             users = self.pool.get('res.users')
+            if self.search_count(cr, uid, [('id', 'in', ids), ('code', '=', 'en_US')], context=context):
+                raise UserError(_("Base Language 'en_US' can not be desactivated!"))
 
             for current_id in ids:
                 current_language = self.browse(cr, uid, current_id, context=context)