diff --git a/include/kernel.h b/include/kernel.h
index 59419549d9b4..c144a4052240 100644
--- a/include/kernel.h
+++ b/include/kernel.h
@@ -1574,6 +1574,7 @@ __syscall int64_t k_uptime_ticks(void);
  */
 static inline int64_t k_uptime_get(void)
 {
+	// ToDo casts: here and intern
 	return k_ticks_to_ms_floor64(k_uptime_ticks());
 }
 
diff --git a/include/sys/time_units.h b/include/sys/time_units.h
index f719230ed291..f3cfdf8afe82 100644
--- a/include/sys/time_units.h
+++ b/include/sys/time_units.h
@@ -129,8 +129,9 @@ static TIME_CONSTEXPR ALWAYS_INLINE uint64_t z_tmcvt(uint64_t t, uint32_t from_h
 	} else {
 		if (result32) {
 			return (uint32_t)((t * to_hz + off) / from_hz);
-		} else {
-			return (t * to_hz + off) / from_hz;
+		} 
+		else {
+			return (t / from_hz) * to_hz + ((t % from_hz) * to_hz + off) / from_hz;
 		}
 	}
 }
diff --git a/lib/posix/clock.c b/lib/posix/clock.c
index c36f2401cc4c..547420242ba0 100644
--- a/lib/posix/clock.c
+++ b/lib/posix/clock.c
@@ -27,7 +27,6 @@ static struct k_spinlock rt_clock_base_lock;
  */
 int z_impl_clock_gettime(clockid_t clock_id, struct timespec *ts)
 {
-	uint64_t elapsed_nsecs;
 	struct timespec base;
 	k_spinlock_key_t key;
 
@@ -48,9 +47,14 @@ int z_impl_clock_gettime(clockid_t clock_id, struct timespec *ts)
 		return -1;
 	}
 
-	elapsed_nsecs = k_ticks_to_ns_floor64(k_uptime_ticks());
-	ts->tv_sec = (int32_t) (elapsed_nsecs / NSEC_PER_SEC);
-	ts->tv_nsec = (int32_t) (elapsed_nsecs % NSEC_PER_SEC);
+	uint64_t ticks = k_uptime_ticks();
+	uint64_t elapsed_secs = k_ticks_to_ms_floor64(ticks) / MSEC_PER_SEC;
+	uint64_t nremainder = ticks - k_ms_to_ticks_floor64(MSEC_PER_SEC * elapsed_secs);
+
+	ts->tv_sec = (time_t) elapsed_secs;
+	/* For ns 32 bit conversion can be used since its smaller than 1sec. */
+	ts->tv_nsec = (int32_t) k_ticks_to_ns_floor32(nremainder);
+
 
 	ts->tv_sec += base.tv_sec;
 	ts->tv_nsec += base.tv_nsec;