diff --git a/Text/LanguageDetect.php b/Text/LanguageDetect.php
index 850b1be..1bcc91c 100644
--- a/Text/LanguageDetect.php
+++ b/Text/LanguageDetect.php
@@ -1658,9 +1658,9 @@ protected function _convertToNameMode($lang, $convertKey = false)
         foreach ($lang as $key => $val) {
             if ($convertKey) {
                 $newkey = Text_LanguageDetect_ISO639::$method($key);
-                $newlang[$newkey] = $val;
+                $newlang[$newkey ?: ''] = $val;
             } else {
-                $newlang[$key] = Text_LanguageDetect_ISO639::$method($val);
+                $newlang[$key ?: ''] = Text_LanguageDetect_ISO639::$method($val);
             }
         }
         return $newlang;