diff --git a/NetBiblio.php b/NetBiblio.php
index 4616bc7..cc4faf7 100644
--- a/NetBiblio.php
+++ b/NetBiblio.php
@@ -210,6 +210,8 @@ class NetBiblio extends WebService
 
         // add hash, client and login into zip file uri
         $books = array_map(function($b) {
+            $b['files']['cacheable_uri'] = isset($b['files']['zip']['uri']) ? $b['files']['zip']['uri'] : false;
+
             if(strlen($this->login) > 0 && isset($b['files']['zip']['uri'])) {
                 $key = 'babf2cfbe2633c3082f8cfffdb3d9008b4b3b300';
                 $code = sprintf("%05u", $b['code']);