diff --git a/addons/membership/membership.py b/addons/membership/membership.py
index 703fb872376..ffef066289c 100644
--- a/addons/membership/membership.py
+++ b/addons/membership/membership.py
@@ -402,6 +402,15 @@ class Product(osv.osv):
 class Invoice(osv.osv):
     _inherit = 'account.invoice'
 
+    def action_cancel_draft(self, cr, uid, ids, context=None):
+        member_line_obj = self.pool.get('membership.membership_line')
+        for invoice in self.browse(cr, uid, ids, context=context):
+            mlines = member_line_obj.search(cr, uid,
+                    [('account_invoice_line', 'in',
+                        [l.id for l in invoice.invoice_line])])
+            member_line_obj.write(cr, uid, mlines, {'date_cancel': False}, context=context)
+        return super(Invoice, self).action_cancel_draft(cr, uid, ids, context=context)
+
     def action_cancel(self, cr, uid, ids, context=None):
         '''Create a 'date_cancel' on the membership_line object'''
         member_line_obj = self.pool.get('membership.membership_line')
diff --git a/addons/website/models/res_config.py b/addons/website/models/res_config.py
index ab90cb3615a..c3cdde7ec6f 100644
--- a/addons/website/models/res_config.py
+++ b/addons/website/models/res_config.py
@@ -10,7 +10,7 @@ class website_config_settings(osv.osv_memory):
         'website_name': fields.related('website_id', 'name', type="char", string="Website Name"),
 
         'language_ids': fields.related('website_id', 'language_ids', type='many2many', relation='res.lang', string='Languages'),
-        'default_lang_id': fields.related('website_id', 'default_lang_id', type='many2one', relation='res.lang', string='Default language'),
+        'default_lang_id': fields.related('website_id', 'default_lang_id', type='many2one', relation='res.lang', string='Default language', required=True),
         'default_lang_code': fields.related('website_id', 'default_lang_code', type="char", string="Default language code"),
         'google_analytics_key': fields.related('website_id', 'google_analytics_key', type="char", string='Google Analytics Key'),
         
diff --git a/addons/website/models/website.py b/addons/website/models/website.py
index 83d0cd79c9d..d1b6353e582 100644
--- a/addons/website/models/website.py
+++ b/addons/website/models/website.py
@@ -157,7 +157,7 @@ class website(osv.osv):
         'domain': fields.char('Website Domain'),
         'company_id': fields.many2one('res.company', string="Company"),
         'language_ids': fields.many2many('res.lang', 'website_lang_rel', 'website_id', 'lang_id', 'Languages'),
-        'default_lang_id': fields.many2one('res.lang', string="Default language"),
+        'default_lang_id': fields.many2one('res.lang', string="Default language", required=True),
         'default_lang_code': fields.related('default_lang_id', 'code', type="char", string="Default language code", store=True),
         'social_twitter': fields.char('Twitter Account'),
         'social_facebook': fields.char('Facebook Account'),