diff --git a/RPtoRFX_CarrierAppointment.ftl b/RPtoRFX_CarrierAppointment.ftl
index 1ec5c55..2f48369 100644
--- a/RPtoRFX_CarrierAppointment.ftl
+++ b/RPtoRFX_CarrierAppointment.ftl
@@ -15,7 +15,7 @@
 			   "unloading_appointment" : "false",
 			   "load_appointment" : "true",
                "planned_load_start_datetime : "${DateTimeUTCtoRfxLocale(appointment.Slot.StartDateTime,time_zone_rfx)}",
-               "planned_load_end_datetime": "${AddSecondsToDatetime(appointment.Slot.StartDateTime,appointment.Slot.DurationInSeconds)?iso_nz(time_zone_rfx)}"
+               "planned_load_end_datetime": "${AddSecondsToDatetime(appointment.Slot.StartDateTime,appointment.Slot.DurationInSeconds?number)?iso_nz(time_zone_rfx)}"
 
 		   <#break>
 
@@ -23,7 +23,7 @@
 		       "unloading_appointment" : "true",
 			   "load_appointment" : "false",
 			   "planned_unloading_start_datetime : "${DateTimeUTCtoRfxLocale(appointment.Slot.StartDateTime?iso_nz(time_zone_rfx))}",
-               "planned_unloading_end_datetime": "${AddSecondsToDatetime(appointment.Slot.StartDateTime,appointment.Slot.DurationInSeconds)?iso_nz(time_zone_rfx)}"
+               "planned_unloading_end_datetime": "${AddSecondsToDatetime(appointment.Slot.StartDateTime,appointment.Slot.DurationInSeconds?number)?iso_nz(time_zone_rfx)}"
 		   <#break>
 	       <#default>
 	         <#stop "appointment.AppointmentType not implemented" >