diff --git a/addons/auth_signup/controllers/main.py b/addons/auth_signup/controllers/main.py
index 82219be6930..d4eb9ec7ec4 100644
--- a/addons/auth_signup/controllers/main.py
+++ b/addons/auth_signup/controllers/main.py
@@ -124,7 +124,7 @@ class AuthSignupHome(Home):
         if values.get('password') != qcontext.get('confirm_password'):
             raise UserError(_("Passwords do not match; please retype them."))
         supported_lang_codes = [code for code, _ in request.env['res.lang'].get_installed()]
-        lang = request.context.get('lang', '').split('_')[0]
+        lang = request.context.get('lang', '')
         if lang in supported_lang_codes:
             values['lang'] = lang
         self._signup_with_values(qcontext.get('token'), values)