diff --git a/htdocs/contrat/class/contrat.class.php b/htdocs/contrat/class/contrat.class.php
index 202a3dc2a0d..958f14f8911 100644
--- a/htdocs/contrat/class/contrat.class.php
+++ b/htdocs/contrat/class/contrat.class.php
@@ -693,8 +693,8 @@ class Contrat extends CommonObject
 				// fetch optionals attributes and labels
 				$line->fetch_optionals($line->id,$extralabelsline);
 
-				$this->lines[]			= $line;
-				$this->lines_id_index_mapper[$line->id] = key($this->lines);
+				$this->lines[$i]			= $line;
+				$this->lines_id_index_mapper[$line->id] = $i;
 
 				//dol_syslog("1 ".$line->desc);
 				//dol_syslog("2 ".$line->product_desc);