diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index bc831baeddf..5999f9e8882 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -4673,6 +4673,7 @@ class Form
 	{
 		global $db;
 
+		require_once DOL_DOCUMENT_ROOT .'/categories/class/categorie.class.php';
 		$cat = new Categorie($db);
 		$categories = $cat->containing($id, $type);