--- modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
+++ modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationUrl.php
@@ -130,7 +130,7 @@
     }
     $languages = array_flip(array_keys($this->languageManager->getLanguages()));
     // Language can be passed as an option, or we go for current URL language.
-    if (!isset($options['language'])) {
+    if (!isset($options['language']) || $options['language']->getID() === 'und') {
       $language_url = $this->languageManager->getCurrentLanguage(LanguageInterface::TYPE_URL);
       $options['language'] = $language_url;
     }