diff --git a/htdocs/fourn/commande/card.php b/htdocs/fourn/commande/card.php
index 5a31e6737b0..6d28b7bbaed 100644
--- a/htdocs/fourn/commande/card.php
+++ b/htdocs/fourn/commande/card.php
@@ -407,7 +407,7 @@ if (empty($reshook)) {
 	}
 
 	// Add a product line
-	if ($action == 'addline' && GETPOST('submitforalllines', 'aZ09') && GETPOST('vatforalllines', 'alpha') && $usercancreate) {
+	if ($action == 'addline' && GETPOST('submitforalllines', 'aZ09') && GETPOST('vatforalllines', 'alpha') !== '' && $usercancreate) {
 		// Define new vat_rate for all lines
 		$vat_rate = (GETPOST('vatforalllines') ? GETPOST('vatforalllines') : 0);
 		$vat_rate = str_replace('*', '', $vat_rate);