diff --git a/htdocs/mrp/class/mo.class.php b/htdocs/mrp/class/mo.class.php
index 09f4ad8d268..0a953ea869c 100644
--- a/htdocs/mrp/class/mo.class.php
+++ b/htdocs/mrp/class/mo.class.php
@@ -25,6 +25,7 @@
 
 // Put here all includes required by your class file
 require_once DOL_DOCUMENT_ROOT.'/core/class/commonobject.class.php';
+require_once DOL_DOCUMENT_ROOT.'/core/class/commonobjectline.class.php';
 //require_once DOL_DOCUMENT_ROOT . '/societe/class/societe.class.php';
 //require_once DOL_DOCUMENT_ROOT . '/product/class/product.class.php';