diff --git a/NetBiblio.php b/NetBiblio.php
index 50cf652..7143dc6 100644
--- a/NetBiblio.php
+++ b/NetBiblio.php
@@ -338,7 +338,8 @@ class NetBiblio extends WebService
         $books = array_map(function($b) {
             if(strlen($this->login) > 0 && isset($b['files']['zip']['uri'])) {
                 $key = 'babf2cfbe2633c3082f8cfffdb3d9008b4b3b300';
-                $hash = sha1($this->client.$this->login.$key.$b['code'].date('Ymd'));
+                $code = sprintf("%05u", $b['code']);
+                $hash = sha1($this->client.$this->login.$key.$code.date('Ymd'));
 
                 $b['files']['zip']['uri'] = str_replace(array(
                     '{client}',