diff --git a/cataloguing/value_builder/unimarc_leader.pl b/cataloguing/value_builder/unimarc_leader.pl
index 838f5a88f0..0bcbb04ebb 100755
--- a/cataloguing/value_builder/unimarc_leader.pl
+++ b/cataloguing/value_builder/unimarc_leader.pl
@@ -33,17 +33,17 @@ sub plugin_javascript {
     my $function_name = $field_number;
     my $res           = "
 <script>
-function Blur$function_name(subfield_managed) {
-	var leader_length = document.getElementById(\"$field_number\").value.length;
+function Blur$function_name(event) {
+    var leader_length = document.getElementById(event.data.id).value.length;
     if (leader_length != 24 && leader_length !=0) {
         alert(_('leader has an incorrect size: ' + leader_length + ' instead of 24 chars'));
     }
-    return 1;
 }
 
-function Clic$function_name(i) {
-	defaultvalue=document.getElementById(\"$field_number\").value;
-	newin=window.open(\"../cataloguing/plugin_launcher.pl?plugin_name=unimarc_leader.pl&index=$field_number&result=\"+defaultvalue,\"unimarc_field_100\",'width=1000,height=600,toolbar=false,scrollbars=yes');
+function Clic$function_name(event) {
+    event.preventDefault();
+    defaultvalue=document.getElementById(event.data.id).value;
+    newin=window.open(\"../cataloguing/plugin_launcher.pl?plugin_name=unimarc_leader.pl&index=\" + event.data.id + \"&result=\"+defaultvalue,\"unimarc_field_100\",'width=1000,height=600,toolbar=false,scrollbars=yes');
 
 }
 </script>