diff --git a/lib/SimpleSAML/Locale/Language.php b/lib/SimpleSAML/Locale/Language.php
index 939bcba355a429c2fa6fb6850fa1a182dcbec26a..054557bd2974db6191c6077f2e0d149f0df42385 100644
--- a/lib/SimpleSAML/Locale/Language.php
+++ b/lib/SimpleSAML/Locale/Language.php
@@ -333,8 +333,8 @@ class Language
      */
     public function getLanguageCodeAlias($langcode)
     {
-        if (isset($this->defaultLanguageMap[$langcode])) {
-            return $this->defaultLanguageMap[$langcode];
+        if (isset(self::$defaultLanguageMap[$langcode])) {
+            return self::$defaultLanguageMap[$langcode];
         }
         // No alias found, which is fine
         return null;