diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 51171f2367..e0b0389b8e 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -1777,8 +1777,8 @@ private:
 	void mmc_shuttle (MIDI::MachineControl &mmc, float speed, bool forw);
 	void mmc_record_enable (MIDI::MachineControl &mmc, size_t track, bool enabled);
 
-	struct timeval last_mmc_step;
-	double step_speed;
+	int64_t _last_mmc_step;
+	double  step_speed;
 
 	typedef std::function<bool()> MidiTimeoutCallback;
 	typedef std::list<MidiTimeoutCallback> MidiTimeoutList;
diff --git a/libs/ardour/session_midi.cc b/libs/ardour/session_midi.cc
index 28e9160924..0f13d47d2f 100644
--- a/libs/ardour/session_midi.cc
+++ b/libs/ardour/session_midi.cc
@@ -207,21 +207,14 @@ Session::mmc_step (MIDI::MachineControl &/*mmc*/, int steps)
 		return;
 	}
 
-	struct timeval now;
-	struct timeval diff = { 0, 0 };
+	int64_t now  = g_get_monotonic_time ();
+	int64_t diff = now - _last_mmc_step;
 
-	gettimeofday (&now, 0);
-
-	timersub (&now, &last_mmc_step, &diff);
-
-	gettimeofday (&now, 0);
-	timersub (&now, &last_mmc_step, &diff);
-
-	if (last_mmc_step.tv_sec != 0 && (diff.tv_usec + (diff.tv_sec * 1000000)) < _engine.usecs_per_cycle()) {
+	if (_last_mmc_step != 0 && diff < _engine.usecs_per_cycle()) {
 		return;
 	}
 
-	double diff_secs = diff.tv_sec + (diff.tv_usec / 1000000.0);
+	double diff_secs = diff * 1e-6;
 	double cur_speed = (((steps * 0.5) * timecode_frames_per_second()) / diff_secs) / timecode_frames_per_second();
 
 	if (_transport_fsm->transport_speed() == 0 || cur_speed * _transport_fsm->transport_speed() < 0) {
@@ -243,7 +236,7 @@ Session::mmc_step (MIDI::MachineControl &/*mmc*/, int steps)
 #endif
 
 	request_transport_speed_nonzero (step_speed);
-	last_mmc_step = now;
+	_last_mmc_step = now;
 
 	if (!step_queued) {
 		if (midi_control_ui) {
@@ -654,15 +647,9 @@ Session::send_immediate_mmc (MachineControlCommand c)
 bool
 Session::mmc_step_timeout ()
 {
-	struct timeval now;
-	struct timeval diff;
-	double diff_usecs;
-	gettimeofday (&now, 0);
+	int64_t diff_usecs = g_get_monotonic_time () - _last_mmc_step;
 
-	timersub (&now, &last_mmc_step, &diff);
-	diff_usecs = diff.tv_sec * 1000000 + diff.tv_usec;
-
-	if (diff_usecs > 1000000.0 || fabs (_transport_fsm->transport_speed()) < 0.0000001) {
+	if (diff_usecs > 1000000 || fabs (_transport_fsm->transport_speed()) < 0.0000001) {
 		/* too long or too slow, stop transport */
 		request_stop ();
 		step_queued = false;
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index 37b2a460a8..097f839a51 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -179,7 +179,7 @@ Session::pre_engine_init (string fullpath)
 	   definition.
 	*/
 
-	timerclear (&last_mmc_step);
+	_last_mmc_step = 0;
 	_processing_prohibited.store (0);
 	_record_status.store (Disabled);
 	_playback_load.store (100);