diff --git a/APPL/MLD/opdr_edit_uren.asp b/APPL/MLD/opdr_edit_uren.asp
index 172fb31aa5..b811f8a906 100644
--- a/APPL/MLD/opdr_edit_uren.asp
+++ b/APPL/MLD/opdr_edit_uren.asp
@@ -98,10 +98,11 @@ oRs.Close();
     <script type="text/javascript">
         var anyChange = false; // Voorkom te veel refreshes
 <%      function getWeekString(datum) {
-          var yearStart = new Date(datum.getFullYear(), 0, 1);
-          var dayOfYear = (datum.getTime() - yearStart.getTime()) / oneDay + 1;
-          var weekNr = Math.ceil(dayOfYear / 7);
-          return datum.getFullYear() + "-" + weekNr;
+          var sql = "SELECT TO_CHAR({0}, 'IYYY-IW') weeknr FROM DUAL".format(datum.toSQL());
+          var oRs = Oracle.Execute(sql);
+          var txt = oRs("weeknr").Value;
+          oRs.Close()
+          return txt;
         }
 %>      FcltMgr.setTitle(L("lcl_mld_ord_weeklijst") + "<%=getWeekString(datefrom)%>");