diff --git a/examples/simulate_iau.f90 b/examples/simulate_iau.f90
index fcb4e4696ed3347f4d799ac72fa44f5a44ae679b..3867c408c4ce2d9a9abb58e9a9179a33b776667f 100644
--- a/examples/simulate_iau.f90
+++ b/examples/simulate_iau.f90
@@ -21,13 +21,13 @@ program simulate_iau
   
   write (0,*) "Assign values ..."
   
-  start_date = "2016-01-01T00:00:00"
-  stop_date  = "2016-01-02T00:00:00"  
+  start_date = t_datetime("2016-01-01T00:00:00")
+  stop_date  = t_datetime("2016-01-02T00:00:00")  
 
-  time_step = "PT15M"
+  time_step = t_timedelta("PT15M")
   dtime = 900.0
   
-  iau_time_shift = "-PT1H30M"
+  iau_time_shift = t_timedelta("-PT1H30M")
   dt_shift = -5400.0
 
   write (0,*) "Prepare time loop ..."