diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 82dff7e6ac7..c543fd436a2 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -2354,6 +2354,8 @@ class Form
 		{
 			require_once DOL_DOCUMENT_ROOT.'/product/class/product.class.php';
 			require_once DOL_DOCUMENT_ROOT.'/product/dynamic_price/class/price_parser.class.php';
+			require_once DOL_DOCUMENT_ROOT.'/core/lib/product.lib.php';
+
 			$num = $this->db->num_rows($result);
 
 			$events = null;
@@ -2882,6 +2884,7 @@ class Form
 		if ($result)
 		{
 			require_once DOL_DOCUMENT_ROOT.'/product/dynamic_price/class/price_parser.class.php';
+			require_once DOL_DOCUMENT_ROOT.'/core/lib/product.lib.php';
 
 			$num = $this->db->num_rows($result);