diff --git a/libraries/AP_HAL_SITL/sitl_gps.cpp b/libraries/AP_HAL_SITL/sitl_gps.cpp
index d91fbe05e7..3c9c9e8ba2 100644
--- a/libraries/AP_HAL_SITL/sitl_gps.cpp
+++ b/libraries/AP_HAL_SITL/sitl_gps.cpp
@@ -179,10 +179,10 @@ static void gps_time(uint16_t *time_week, uint32_t *time_week_ms)
     simulation_timeval(&tv);
     const uint32_t epoch = 86400*(10*365 + (1980-1969)/4 + 1 + 6 - 2) - (GPS_LEAPSECONDS_MILLIS / 1000ULL);
     uint32_t epoch_seconds = tv.tv_sec - epoch;
-    *time_week = epoch_seconds / SEC_PER_WEEK;
+    *time_week = epoch_seconds / AP_SEC_PER_WEEK;
     uint32_t t_ms = tv.tv_usec / 1000;
     // round time to nearest 200ms
-    *time_week_ms = (epoch_seconds % SEC_PER_WEEK) * MSEC_PER_SEC + ((t_ms/200) * 200);
+    *time_week_ms = (epoch_seconds % AP_SEC_PER_WEEK) * AP_MSEC_PER_SEC + ((t_ms/200) * 200);
 }
 
 /*