diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 03d81d4fd64..3c76d25df8b 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -35,6 +35,7 @@
  *    \ingroup    produit
  *    \brief      File of class to manage predefined products or services
  */
+require_once DOL_DOCUMENT_ROOT.'/core/lib/product.lib.php';
 require_once DOL_DOCUMENT_ROOT.'/core/class/commonobject.class.php';
 require_once DOL_DOCUMENT_ROOT.'/product/class/productbatch.class.php';
 require_once DOL_DOCUMENT_ROOT.'/product/stock/class/entrepot.class.php';