diff --git a/sw/airborne/avr/sys_time_hw.h b/sw/airborne/avr/sys_time_hw.h
index 5a26de7d7d..3d96a60c76 100644
--- a/sw/airborne/avr/sys_time_hw.h
+++ b/sw/airborne/avr/sys_time_hw.h
@@ -101,7 +101,7 @@ extern volatile uint8_t tmr2_ov_cnt;
 extern volatile bool_t tmr2_overflow;
 #endif
 
-#define TICKS_PER_SEC (CLOCK * 1e6 / 1024 * 256)
+#define TICKS_PER_SEC (CLOCK * 1e6 / 1024)
 
 #if CLOCK == 8
 static inline bool_t sys_time_periodic( void ) {
diff --git a/sw/airborne/infrared.c b/sw/airborne/infrared.c
index 0af3e6495d..deea30d5b1 100644
--- a/sw/airborne/infrared.c
+++ b/sw/airborne/infrared.c
@@ -198,7 +198,7 @@ uint8_t calib_status = NO_CALIB;
 void ground_calibrate( bool_t triggered ) {
   switch (calib_status) {
   case NO_CALIB:
-    if (cpu_time < MAX_DELAY_FOR_CALIBRATION && pprz_mode == PPRZ_MODE_AUTO1 ) {
+    if (cpu_time_sec < MAX_DELAY_FOR_CALIBRATION && pprz_mode == PPRZ_MODE_AUTO1 ) {
       calib_status = WAITING_CALIB_CONTRAST;
       DOWNLINK_SEND_CALIB_START();
     }
diff --git a/sw/airborne/main_ap.c b/sw/airborne/main_ap.c
index c79d758554..5048f1019a 100644
--- a/sw/airborne/main_ap.c
+++ b/sw/airborne/main_ap.c
@@ -300,7 +300,7 @@ static void navigation_task( void ) {
   static uint8_t last_pprz_mode;
   /** Test if we lost the GPS */
   if (!GpsFixValid() ||
-      (cpu_time - last_gps_msg_t > FAILSAFE_DELAY_WITHOUT_GPS)) {
+      (cpu_time_sec - last_gps_msg_t > FAILSAFE_DELAY_WITHOUT_GPS)) {
     /** If aircraft is launch and is in autonomus mode, go into
 	PPRZ_MODE_GPS_OUT_OF_ORDER mode (Failsafe). */
     if (launch && (pprz_mode == PPRZ_MODE_AUTO2 ||
@@ -417,7 +417,7 @@ void periodic_task_ap( void ) {
 
   if (!_1Hz) {
     if (estimator_flight_time) estimator_flight_time++;
-    cpu_time++;
+    cpu_time_sec++;
     stage_time_ds = (int16_t)(stage_time_ds+.5);
     stage_time++;
     block_time++;
@@ -450,7 +450,7 @@ void periodic_task_ap( void ) {
 	estimator_hspeed_mod > MIN_SPEED_FOR_TAKEOFF) {
       estimator_flight_time = 1;
       launch = TRUE; /* Not set in non auto launch */
-      DOWNLINK_SEND_TAKEOFF(&cpu_time);
+      DOWNLINK_SEND_TAKEOFF(&cpu_time_sec);
     }
     break;