diff --git a/src/system/arduino/esp32/system.c b/src/system/arduino/esp32/system.c
index a9eab813c..8f0773751 100644
--- a/src/system/arduino/esp32/system.c
+++ b/src/system/arduino/esp32/system.c
@@ -135,13 +135,13 @@ int z_sleep_s(size_t time) { return sleep(time); }
 /*------------------ Instant ------------------*/
 z_clock_t z_clock_now(void) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
     return now;
 }
 
 unsigned long z_clock_elapsed_us(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000);
     return elapsed;
@@ -149,7 +149,7 @@ unsigned long z_clock_elapsed_us(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000000);
     return elapsed;
@@ -157,7 +157,7 @@ unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_s(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = now.tv_sec - instant->tv_sec;
     return elapsed;
diff --git a/src/system/espidf/system.c b/src/system/espidf/system.c
index 8a655cf0d..a93c5b0e5 100644
--- a/src/system/espidf/system.c
+++ b/src/system/espidf/system.c
@@ -136,13 +136,13 @@ int z_sleep_s(size_t time) { return sleep(time); }
 /*------------------ Instant ------------------*/
 z_clock_t z_clock_now(void) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
     return now;
 }
 
 unsigned long z_clock_elapsed_us(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000);
     return elapsed;
@@ -150,7 +150,7 @@ unsigned long z_clock_elapsed_us(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000000);
     return elapsed;
@@ -158,7 +158,7 @@ unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_s(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = now.tv_sec - instant->tv_sec;
     return elapsed;
diff --git a/src/system/unix/system.c b/src/system/unix/system.c
index 875bc5f2b..990619dac 100644
--- a/src/system/unix/system.c
+++ b/src/system/unix/system.c
@@ -156,13 +156,13 @@ int z_sleep_s(size_t time) { return sleep(time); }
 /*------------------ Instant ------------------*/
 z_clock_t z_clock_now(void) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
     return now;
 }
 
 unsigned long z_clock_elapsed_us(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000);
     return elapsed;
@@ -170,7 +170,7 @@ unsigned long z_clock_elapsed_us(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000000);
     return elapsed;
@@ -178,7 +178,7 @@ unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_s(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = now.tv_sec - instant->tv_sec;
     return elapsed;
diff --git a/src/system/zephyr/system.c b/src/system/zephyr/system.c
index 28ce1d303..20e54d146 100644
--- a/src/system/zephyr/system.c
+++ b/src/system/zephyr/system.c
@@ -150,13 +150,13 @@ int z_sleep_s(size_t time) {
 /*------------------ Instant ------------------*/
 z_clock_t z_clock_now(void) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
     return now;
 }
 
 unsigned long z_clock_elapsed_us(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000);
     return elapsed;
@@ -164,7 +164,7 @@ unsigned long z_clock_elapsed_us(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = (1000 * (now.tv_sec - instant->tv_sec) + (now.tv_nsec - instant->tv_nsec) / 1000000);
     return elapsed;
@@ -172,7 +172,7 @@ unsigned long z_clock_elapsed_ms(z_clock_t *instant) {
 
 unsigned long z_clock_elapsed_s(z_clock_t *instant) {
     z_clock_t now;
-    clock_gettime(CLOCK_REALTIME, &now);
+    clock_gettime(CLOCK_MONOTONIC, &now);
 
     unsigned long elapsed = now.tv_sec - instant->tv_sec;
     return elapsed;