diff --git a/htdocs/supplier_proposal/class/supplier_proposal.class.php b/htdocs/supplier_proposal/class/supplier_proposal.class.php
index 0c8410213afd91cb63d08cefe1dfd88372b0dc28..1d27e7c49862b2f72e5f927470ca45ff8f9288a9 100644
--- a/htdocs/supplier_proposal/class/supplier_proposal.class.php
+++ b/htdocs/supplier_proposal/class/supplier_proposal.class.php
@@ -2841,7 +2841,7 @@ class SupplierProposalLine  extends CommonObjectLine
         $sql.= " ".price2num($this->localtax2_tx).",";
 		$sql.= " '".$this->localtax1_type."',";
 		$sql.= " '".$this->localtax2_type."',";
-        $sql.= " ".price2num($this->subprice).",";
+        $sql.= " ".(!empty($this->subprice)?price2num($this->subprice):"null").",";
         $sql.= " ".price2num($this->remise_percent).",";
         $sql.= " ".(isset($this->info_bits)?"'".$this->info_bits."'":"null").",";
         $sql.= " ".price2num($this->total_ht).",";