diff --git a/library/Class/Testing/Yaz.php b/library/Class/Testing/Yaz.php
index 2b775e1b8a02ab483aaa8a62648bff4e9172d287..ab103b5f0786536383ac5161d281215160785267 100644
--- a/library/Class/Testing/Yaz.php
+++ b/library/Class/Testing/Yaz.php
@@ -26,7 +26,7 @@ class Class_Testing_Yaz {
 
   public function marcToMarcXml($unimarc) {
     if(!$unimarc)
-      return '';
+      return [];
 
     $filename = $this->_writeUnimarcInFile($unimarc);