diff --git a/book.php b/book.php
index e870a58..65a6083 100644
--- a/book.php
+++ b/book.php
@@ -12,6 +12,7 @@ require_once('author.php');
 require_once('tag.php');
 require_once ("customcolumn.php");
 require_once('data.php');
+require_once('php-epub-meta/tbszip.php');
 require_once('php-epub-meta/epub.php');
 
 // Silly thing because PHP forbid string concatenation in class const