diff --git a/OPDS_renderer.php b/OPDS_renderer.php
index a8da8a3..01c8a48 100644
--- a/OPDS_renderer.php
+++ b/OPDS_renderer.php
@@ -217,7 +217,7 @@ class OPDSRenderer
         }
         
         $lang = $entry->book->getLanguages ();
-        if (!is_null ($lang)) {
+        if (!empty ($lang)) {
             self::getXmlStream ()->startElement ("dcterms:language");
                 self::getXmlStream ()->text ($lang);
             self::getXmlStream ()->endElement ();