diff --git a/addons/website/models/__init__.py b/addons/website/models/__init__.py
index 173075aafbf..77c01e012a0 100644
--- a/addons/website/models/__init__.py
+++ b/addons/website/models/__init__.py
@@ -18,3 +18,4 @@ from . import res_company
 from . import res_partner
 from . import res_users
 from . import res_config_settings
+from . import res_lang
diff --git a/addons/website/models/res_config_settings.py b/addons/website/models/res_config_settings.py
index 73c95fc0530..875e9d1ff0c 100644
--- a/addons/website/models/res_config_settings.py
+++ b/addons/website/models/res_config_settings.py
@@ -18,7 +18,7 @@ class ResConfigSettings(models.TransientModel):
     website_domain = fields.Char('Website Domain', related='website_id.domain', readonly=False)
     website_country_group_ids = fields.Many2many(related='website_id.country_group_ids', readonly=False)
     website_company_id = fields.Many2one(related='website_id.company_id', string='Website Company', readonly=False)
-    language_ids = fields.Many2many(related='website_id.language_ids', relation='res.lang', readonly=False)
+    language_ids = fields.Many2many(related='website_id.language_ids', relation='res.lang', readonly=False, required=True)
     language_count = fields.Integer(string='Number of languages', compute='_compute_language_count', readonly=True)
     website_default_lang_id = fields.Many2one(
         string='Default language', related='website_id.default_lang_id', readonly=False,
@@ -106,7 +106,9 @@ class ResConfigSettings(models.TransientModel):
     def _onchange_language_ids(self):
         # If current default language is removed from language_ids
         # update the website_default_lang_id
-        if self.language_ids and self.website_default_lang_id not in self.language_ids:
+        if not self.language_ids:
+            self.website_default_lang_id = False
+        elif self.website_default_lang_id not in self.language_ids:
             self.website_default_lang_id = self.language_ids[0]
 
     @api.depends('language_ids')
diff --git a/addons/website/models/res_lang.py b/addons/website/models/res_lang.py
new file mode 100644
index 00000000000..147ff26c6d0
--- /dev/null
+++ b/addons/website/models/res_lang.py
@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import api, models, _
+from odoo.exceptions import UserError
+
+
+class Lang(models.Model):
+    _inherit = "res.lang"
+
+    @api.multi
+    def write(self, vals):
+        if 'active' in vals and not vals['active']:
+            if self.env['website'].search([('language_ids', 'in', self._ids)]):
+                raise UserError(_("Cannot deactivate a language that is currently used on a website."))
+        return super(Lang, self).write(vals)