diff --git a/src/http.c b/src/http.c
index e0cbce5..050766e 100644
--- a/src/http.c
+++ b/src/http.c
@@ -22,7 +22,6 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <string.h>
-#include <time.h>
 #include <assert.h>
 
 #include <event2/event.h>
@@ -188,7 +187,6 @@ static void _http_callback_ping(struct evhttp_request *request, void *v_server)
 static void _http_callback_snapshot(struct evhttp_request *request, void *v_exposed) {
 	struct exposed_t *exposed = (struct exposed_t *)v_exposed;
 	struct evbuffer *buf;
-	struct timespec x_timestamp_spec;
 	char x_timestamp_buf[64];
 
 	PROCESS_HEAD_REQUEST;
@@ -196,17 +194,11 @@ static void _http_callback_snapshot(struct evhttp_request *request, void *v_expo
 	assert((buf = evbuffer_new()));
 	assert(!evbuffer_add(buf, (const void *)exposed->picture.data, exposed->picture.size));
 
-	assert(!clock_gettime(CLOCK_REALTIME, &x_timestamp_spec));
-	sprintf(
-		x_timestamp_buf, "%u.%06u",
-		(unsigned)x_timestamp_spec.tv_sec,
-		(unsigned)(x_timestamp_spec.tv_nsec / 1000) // TODO: round?
-	);
-
 	ADD_HEADER("Access-Control-Allow-Origin:", "*");
 	ADD_HEADER("Cache-Control", "no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0");
 	ADD_HEADER("Pragma", "no-cache");
 	ADD_HEADER("Expires", "Mon, 3 Jan 2000 12:34:56 GMT");
+	sprintf(x_timestamp_buf, "%.06Lf", now_real_ms());
 	ADD_HEADER("X-Timestamp", x_timestamp_buf);
 	ADD_HEADER("Content-Type", "image/jpeg");
 
@@ -264,10 +256,8 @@ static void _http_callback_stream(struct evhttp_request *request, void *v_server
 static void _http_callback_stream_write(struct bufferevent *buf_event, void *v_client) {
 	struct stream_client_t *client = (struct stream_client_t *)v_client;
 	struct evbuffer *buf;
-	struct timespec x_timestamp_spec;
 
 	assert((buf = evbuffer_new()));
-	assert(!clock_gettime(CLOCK_REALTIME, &x_timestamp_spec));
 
 	if (client->need_initial) {
 		assert(evbuffer_add_printf(buf,
@@ -287,11 +277,10 @@ static void _http_callback_stream_write(struct bufferevent *buf_event, void *v_c
 	assert(evbuffer_add_printf(buf,
 		"Content-Type: image/jpeg" RN
 		"Content-Length: %lu" RN
-		"X-Timestamp: %u.%06u" RN
+		"X-Timestamp: %.06Lf" RN
 		RN,
 		client->server->run->exposed->picture.size * sizeof(*client->server->run->exposed->picture.data),
-		(unsigned)x_timestamp_spec.tv_sec,
-		(unsigned)(x_timestamp_spec.tv_nsec / 1000) // TODO: round?
+		now_real_ms()
 	));
 	assert(!evbuffer_add(buf,
 		(void *)client->server->run->exposed->picture.data,
diff --git a/src/logging.h b/src/logging.h
index fb7618b..59ab28d 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -71,7 +71,7 @@ pthread_mutex_t log_mutex;
 
 #define LOG_ERROR(_x_msg, ...) { \
 		LOGGING_LOCK; \
-		printf("-- ERROR [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+		printf("-- ERROR [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 		LOGGING_UNLOCK; \
 	}
 
@@ -79,24 +79,24 @@ pthread_mutex_t log_mutex;
 		char _buf[1024] = ""; \
 		strerror_r(errno, _buf, 1024); \
 		LOGGING_LOCK; \
-		printf("-- ERROR [%.03Lf tid=%ld] -- " _x_msg ": %s\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__, _buf); \
+		printf("-- ERROR [%.03Lf tid=%ld] -- " _x_msg ": %s\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__, _buf); \
 		LOGGING_UNLOCK; \
 	}
 
 #define LOG_INFO(_x_msg, ...) { \
 		LOGGING_LOCK; \
-		printf("-- INFO  [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+		printf("-- INFO  [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 		LOGGING_UNLOCK; \
 	}
 
 #define LOG_INFO_NOLOCK(_x_msg, ...) { \
-		printf("-- INFO  [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+		printf("-- INFO  [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 	}
 
 #define LOG_PERF(_x_msg, ...) { \
 		if (log_level >= LOG_LEVEL_PERF) { \
 			LOGGING_LOCK; \
-			printf("-- PERF  [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+			printf("-- PERF  [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 			LOGGING_UNLOCK; \
 		} \
 	}
@@ -104,7 +104,7 @@ pthread_mutex_t log_mutex;
 #define LOG_VERBOSE(_x_msg, ...) { \
 		if (log_level >= LOG_LEVEL_VERBOSE) { \
 			LOGGING_LOCK; \
-			printf("-- VERB  [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+			printf("-- VERB  [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 			LOGGING_UNLOCK; \
 		} \
 	}
@@ -112,7 +112,7 @@ pthread_mutex_t log_mutex;
 #define LOG_DEBUG(_x_msg, ...) { \
 		if (log_level >= LOG_LEVEL_DEBUG) { \
 			LOGGING_LOCK; \
-			printf("-- DEBUG [%.03Lf tid=%ld] -- " _x_msg "\n", now_ms_ld(), syscall(SYS_gettid), ##__VA_ARGS__); \
+			printf("-- DEBUG [%.03Lf tid=%ld] -- " _x_msg "\n", now_monotonic_ms(), syscall(SYS_gettid), ##__VA_ARGS__); \
 			LOGGING_UNLOCK; \
 		} \
 	}
diff --git a/src/omx/formatters.h b/src/omx/formatters.h
index e015103..3bcd873 100644
--- a/src/omx/formatters.h
+++ b/src/omx/formatters.h
@@ -35,7 +35,7 @@
 
 #define LOG_OMX_ERROR(_error, _msg, ...) { \
 		LOGGING_LOCK; \
-		printf("-- ERROR [%.03Lf tid=%ld] -- " _msg ": %s\n", now_ms_ld(), \
+		printf("-- ERROR [%.03Lf tid=%ld] -- " _msg ": %s\n", now_monotonic_ms(), \
 			syscall(SYS_gettid), ##__VA_ARGS__, omx_error_to_string(_error)); \
 		LOGGING_UNLOCK; \
 	}
diff --git a/src/stream.c b/src/stream.c
index 155a1a6..0a8d5b0 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -187,7 +187,7 @@ void stream_loop(struct stream_t *stream) {
 					}
 
 					{
-						long double now = now_ms_ld();
+						long double now = now_monotonic_ms();
 
 						if (now < grab_after) {
 							fluency_passed += 1;
@@ -407,7 +407,7 @@ static void *_stream_worker_thread(void *v_ctx) {
 			long double start_time;
 			long double last_comp_time;
 
-			start_time = now_ms_ld();
+			start_time = now_monotonic_ms();
 
 			LOG_DEBUG("Worker %u compressing JPEG from buffer %d ...", ctx->number, ctx->buf_index);
 
@@ -419,7 +419,7 @@ static void *_stream_worker_thread(void *v_ctx) {
 				*ctx->job_start_time = start_time;
 				*ctx->has_job = false;
 
-				last_comp_time = now_ms_ld() - start_time;
+				last_comp_time = now_monotonic_ms() - start_time;
 
 				A_PTHREAD_M_LOCK(ctx->last_comp_time_mutex);
 				*ctx->last_comp_time = last_comp_time;
diff --git a/src/tools.h b/src/tools.h
index ed2107c..7a08738 100644
--- a/src/tools.h
+++ b/src/tools.h
@@ -61,10 +61,10 @@ INLINE unsigned max_u(unsigned a, unsigned b) {
 	return (a > b ? a : b);
 }
 
-INLINE void now_ms(time_t *sec, long *msec) {
+INLINE void now_ms(clockid_t clk_id, time_t *sec, long *msec) {
 	struct timespec spec;
 
-	assert(!clock_gettime(CLOCK_MONOTONIC_RAW, &spec));
+	assert(!clock_gettime(clk_id, &spec));
 	*sec = spec.tv_sec;
 	*msec = round(spec.tv_nsec / 1.0e6);
 
@@ -74,10 +74,18 @@ INLINE void now_ms(time_t *sec, long *msec) {
 	}
 }
 
-INLINE long double now_ms_ld(void) {
+INLINE long double now_monotonic_ms(void) {
 	time_t sec;
 	long msec;
 
-	now_ms(&sec, &msec);
+	now_ms(CLOCK_MONOTONIC_RAW, &sec, &msec);
+	return (long double)sec + ((long double)msec) / 1000;
+}
+
+INLINE long double now_real_ms(void) {
+	time_t sec;
+	long msec;
+
+	now_ms(CLOCK_REALTIME, &sec, &msec);
 	return (long double)sec + ((long double)msec) / 1000;
 }