--- biblio/biblio_theme.inc	2014-09-23 15:01:29.000000000 +0200
+++ biblio/biblio_theme.inc	2014-09-23 15:02:36.000000000 +0200
@@ -568,7 +568,7 @@
   $base = variable_get('biblio_base', 'biblio');
   $link_to_profile = variable_get('biblio_author_link_profile', 0);
   $options = array();
-  $inline = $inline ? "/inline" : "";
+  $inline = isset($inline) && $inline ? "/inline" : "";
 
   if (isset($_GET['sort'])) {
     $options['query']['sort'] = $_GET['sort'];