diff --git a/openedx/core/djangoapps/lang_pref/middleware.py b/openedx/core/djangoapps/lang_pref/middleware.py
index d0a787c5daa..a480c2577ed 100644
--- a/openedx/core/djangoapps/lang_pref/middleware.py
+++ b/openedx/core/djangoapps/lang_pref/middleware.py
@@ -66,6 +66,8 @@ def process_response(self, request, response):  # lint-amnesty, pylint: disable=
 
             # DarkLangMiddleware has already set this cookie
             if DarkLangConfig.current().enabled and get_user_preference(current_user, DARK_LANGUAGE_KEY):
+                new_lang = get_user_preference(current_user, DARK_LANGUAGE_KEY)
+                lang_pref_helpers.set_language_cookie(request, response, new_lang)
                 return response
 
             anonymous_cookie_lang = getattr(request, '_anonymous_user_cookie_lang', None)