diff --git a/htdocs/core/class/html.formmargin.class.php b/htdocs/core/class/html.formmargin.class.php
index 6b7ba7348ff..579b8fe5208 100644
--- a/htdocs/core/class/html.formmargin.class.php
+++ b/htdocs/core/class/html.formmargin.class.php
@@ -63,6 +63,8 @@ class FormMargin
 	{
 		global $conf, $db;
 
+        require_once DOL_DOCUMENT_ROOT . '/compta/facture/class/facture.class.php';
+
 		// Default returned array
 		$marginInfos = array(
 				'pa_products' => 0,