diff --git a/conf.py b/conf.py
index 5b70270c9..5cea2ad50 100644
--- a/conf.py
+++ b/conf.py
@@ -442,7 +442,7 @@ def _generate_alternate_urls(app, pagename, templatename, context, doctree):
         """
         _current_lang = app.config.language or 'en'
         # Replace the context value by its upper-cased value ("FR" instead of "fr")
-        context['language'] = languages_names.get(_current_lang)
+        context['language'] = languages_names.get(_current_lang, _current_lang.upper())
         context['language_code'] = _current_lang
 
         # If the list of languages is not set, assume that the project has no alternate language