diff --git a/htdocs/core/class/conf.class.php b/htdocs/core/class/conf.class.php
index 61ba7b062db..a67c8ce66fa 100644
--- a/htdocs/core/class/conf.class.php
+++ b/htdocs/core/class/conf.class.php
@@ -236,12 +236,12 @@ class Conf
 		if (empty($this->global->MAIN_MENU_SMARTPHONE)) $this->global->MAIN_MENU_SMARTPHONE="eldy_menu.php";	// Use eldy by default because smartphone does not work on all phones
 		if (empty($this->global->MAIN_MENUFRONT_SMARTPHONE)) $this->global->MAIN_MENUFRONT_SMARTPHONE="eldy_menu.php";	// Use eldy by default because smartphone does not work on all phones
 		// Clean var use vat for company
-		if (! isset($conf->global->FACTURE_TVAOPTION)) $conf->global->FACTURE_TVAOPTION=1;
-		else if (! empty($conf->global->FACTURE_TVAOPTION) && ! is_numeric($conf->global->FACTURE_TVAOPTION))
+		if (! isset($this->global->FACTURE_TVAOPTION)) $this->global->FACTURE_TVAOPTION=1;
+		else if (! empty($this->global->FACTURE_TVAOPTION) && ! is_numeric($this->global->FACTURE_TVAOPTION))
 		{
 			// Old value of option, we clean to use new value (0 or 1)
-			if ($conf->global->FACTURE_TVAOPTION != "franchise") $conf->global->FACTURE_TVAOPTION=1;
-			else $conf->global->FACTURE_TVAOPTION=0;
+			if ($this->global->FACTURE_TVAOPTION != "franchise") $this->global->FACTURE_TVAOPTION=1;
+			else $this->global->FACTURE_TVAOPTION=0;
 		}
 		
 		// Variable globales LDAP