diff --git a/src/platforms/posix/px4_layer/drv_hrt.c b/src/platforms/posix/px4_layer/drv_hrt.c
index d40b540b2c5..7c4b39af67e 100644
--- a/src/platforms/posix/px4_layer/drv_hrt.c
+++ b/src/platforms/posix/px4_layer/drv_hrt.c
@@ -133,11 +133,11 @@ int px4_clock_gettime(clockid_t clk_id, struct timespec *tp)
 /*
  * Get system time in us
  */
-unsigned long long hrt_system_time(void)
+uint64_t hrt_system_time(void)
 {
 	struct timespec ts;
 	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
-	return ts_to_abstime(&ts) - px4_timestart;
+	return ts_to_abstime(&ts);
 }
 
 /*
diff --git a/src/platforms/px4_posix.h b/src/platforms/px4_posix.h
index e1b9f3c149d..7a92bf7acf7 100644
--- a/src/platforms/px4_posix.h
+++ b/src/platforms/px4_posix.h
@@ -45,6 +45,7 @@
 #include <fcntl.h>
 #include <poll.h>
 #include <semaphore.h>
+#include <stdint.h>
 
 #if defined(__PX4_QURT)
 #include <dspal_types.h>
@@ -174,9 +175,9 @@ __EXPORT const char 	*px4_get_topic_names(unsigned int *handle);
 /*
  * The UNIX epoch system time following the system clock
  */
-__EXPORT unsigned long long	hrt_system_time(void);
+__EXPORT uint64_t	hrt_system_time(void);
 
-__EXPORT bool			px4_exit_requested(void);
+__EXPORT bool		px4_exit_requested(void);
 #endif
 
 __END_DECLS