diff --git a/htdocs/fourn/class/fournisseur.facture.class.php b/htdocs/fourn/class/fournisseur.facture.class.php
index 494459b66d2..fd393445187 100644
--- a/htdocs/fourn/class/fournisseur.facture.class.php
+++ b/htdocs/fourn/class/fournisseur.facture.class.php
@@ -3387,20 +3387,11 @@ class SupplierInvoiceLine extends CommonObjectLine
 			$this->multicurrency_total_ttc = 0;
 		}
 
+		$fk_product = (int) $this->fk_product;
+		$fk_unit = (int) $this->fk_unit;
+
 		$this->db->begin();
 
-		if (empty($this->fk_product)) {
-			$fk_product = "null";
-		} else {
-			$fk_product = (int) $this->fk_product;
-		}
-
-		if (empty($this->fk_unit)) {
-			$fk_unit = "null";
-		} else {
-			$fk_unit = (int) $this->fk_unit;
-		}
-
 		$sql = "UPDATE ".MAIN_DB_PREFIX."facture_fourn_det SET";
 		$sql .= "  description ='".$this->db->escape($this->description)."'";
 		$sql .= ", ref ='".$this->db->escape($this->ref_supplier ? $this->ref_supplier : $this->ref)."'";