diff --git a/addons/crm/models/crm_lead.py b/addons/crm/models/crm_lead.py
index e7e884165d1..0ce4008ae07 100644
--- a/addons/crm/models/crm_lead.py
+++ b/addons/crm/models/crm_lead.py
@@ -191,7 +191,9 @@ class Lead(models.Model):
         ('correct', 'Correct'),
         ('incorrect', 'Incorrect')], string='Email Quality', compute="_compute_email_state", store=True)
     website = fields.Char('Website', help="Website of the contact", compute="_compute_website", readonly=False, store=True)
-    lang_id = fields.Many2one('res.lang', string='Language', compute='_compute_lang_id', readonly=False, store=True)
+    lang_id = fields.Many2one(
+        'res.lang', string='Language',
+        compute='_compute_lang_id', readonly=False, store=True)
     lang_code = fields.Char(related='lang_id.code')
     lang_active_count = fields.Integer(compute='_compute_lang_active_count')
     # Address fields
@@ -409,10 +411,13 @@ class Lead(models.Model):
         one if set. """
         # prepare cache
         lang_codes = [code for code in self.mapped('partner_id.lang') if code]
-        lang_id_by_code = dict(
-            (code, self.env['res.lang']._lang_get_id(code))
-            for code in lang_codes
-        )
+        if lang_codes:
+            lang_id_by_code = dict(
+                (code, self.env['res.lang']._lang_get_id(code))
+                for code in lang_codes
+            )
+        else:
+            lang_id_by_code = {}
         for lead in self.filtered('partner_id'):
             lead.lang_id = lang_id_by_code.get(lead.partner_id.lang, False)
 
diff --git a/addons/crm/tests/common.py b/addons/crm/tests/common.py
index c50e44c1593..23c93498e7e 100644
--- a/addons/crm/tests/common.py
+++ b/addons/crm/tests/common.py
@@ -127,8 +127,8 @@ class TestCrmCommon(TestSalesCommon, MailCase):
         base_us = cls.env.ref('base.us')
         cls.env['res.lang']._activate_lang('fr_FR')
         cls.env['res.lang']._activate_lang('en_US')
-        cls.lang_fr = cls.env['res.lang']._lang_get('fr_FR')
         cls.lang_en = cls.env['res.lang']._lang_get('en_US')
+        cls.lang_fr = cls.env['res.lang']._lang_get('fr_FR')
 
         # leads
         cls.lead_1 = cls.env['crm.lead'].create({
diff --git a/addons/crm/tests/test_crm_lead.py b/addons/crm/tests/test_crm_lead.py
index 34acfcad160..d33e9b6f4f8 100644
--- a/addons/crm/tests/test_crm_lead.py
+++ b/addons/crm/tests/test_crm_lead.py
@@ -70,6 +70,8 @@ class TestCRMLead(TestCrmCommon):
         lead.write({'partner_id': self.contact_company_1.id})
         for fname in PARTNER_ADDRESS_FIELDS_TO_SYNC:
             self.assertEqual(lead[fname], self.contact_company_1[fname])
+            self.assertEqual(self.contact_company_1.lang, self.lang_en.code)
+            self.assertEqual(lead.lang_id, self.lang_en)
 
     @users('user_sales_leads')
     def test_crm_lead_creation_no_partner(self):
diff --git a/doc/cla/corporate/metrum.md b/doc/cla/corporate/metrum.md
index b64bf351a8b..a04d4dec2be 100644
--- a/doc/cla/corporate/metrum.md
+++ b/doc/cla/corporate/metrum.md
@@ -14,3 +14,4 @@ List of contributors:
 
 Pascal Pelzer pascal.pelzer@metrum.lu https://github.com/PascalPelzer
 Jonathan Nemry jonathan.nemry@metrum.lu https://github.com/JonathanNEMRY
+Lorenzo Ciciotti lorenzo.ciciotti@metrum.lu https://github.com/lorenzo6ioti