diff --git a/sw/airborne/mcu_periph/sys_time.h b/sw/airborne/mcu_periph/sys_time.h
index 407981ddb04..6b137510962 100644
--- a/sw/airborne/mcu_periph/sys_time.h
+++ b/sw/airborne/mcu_periph/sys_time.h
@@ -121,7 +121,7 @@ static inline bool_t sys_time_check_and_ack_timer(tid_t id) {
  * @return current system time as float
  */
 static inline float get_sys_time_float(void) {
-  return (float)(sys_time.nb_sec + sys_time.nb_sec_rem * sys_time.resolution_cpu_ticks);
+  return (float)(sys_time.nb_sec + (float)(sys_time.nb_sec_rem) / sys_time.cpu_ticks_per_sec);
 }