diff --git a/htdocs/fourn/class/fournisseur.facture.class.php b/htdocs/fourn/class/fournisseur.facture.class.php
index c1337452d8a..34609a8fa33 100644
--- a/htdocs/fourn/class/fournisseur.facture.class.php
+++ b/htdocs/fourn/class/fournisseur.facture.class.php
@@ -1383,6 +1383,11 @@ class FactureFournisseur extends CommonInvoice
         if (empty($txlocaltax1)) $txlocaltax1=0;
         if (empty($txlocaltax2)) $txlocaltax2=0;
 
+        if ($rang < 0) {
+            $rangmax = $this->line_max();
+            $rang = $rangmax + 1;
+        }
+        
         $localtaxes_type=getLocalTaxesFromRate($txtva, 0, $mysoc, $this->thirdparty);
 
         // Clean vat code