diff --git a/window-clock.c b/window-clock.c
index 51620d4a..81d33858 100644
--- a/window-clock.c
+++ b/window-clock.c
@@ -123,6 +123,26 @@ const char window_clock_table[14][5][5] = {
 	  { 1,0,0,0,1 } },
 };
 
+static void
+window_clock_start_timer(struct window_mode_entry *wme)
+{
+	struct window_clock_mode_data	*data = wme->data;
+	struct timeval			 tv;
+	struct timespec			 ts;
+	long				 delay;
+
+	clock_gettime(CLOCK_REALTIME, &ts);
+	delay = 1000000 - (ts.tv_nsec / 1000);
+
+	tv.tv_sec = delay / 1000000;
+	tv.tv_usec = delay % 1000000;
+	if (tv.tv_sec < 0 || (tv.tv_sec == 0 && tv.tv_usec <= 0)) {
+		tv.tv_sec = 1;
+		tv.tv_usec = 0;
+	}
+	evtimer_add(&data->timer, &tv);
+}
+
 static void
 window_clock_timer_callback(__unused int fd, __unused short events, void *arg)
 {
@@ -131,23 +151,20 @@ window_clock_timer_callback(__unused int fd, __unused short events, void *arg)
 	struct window_clock_mode_data	*data = wme->data;
 	struct tm			 now, then;
 	time_t				 t;
-	struct timeval			 tv = { .tv_sec = 1 };
 
 	evtimer_del(&data->timer);
-	evtimer_add(&data->timer, &tv);
-
-	if (TAILQ_FIRST(&wp->modes) != wme)
-		return;
 
 	t = time(NULL);
 	gmtime_r(&t, &now);
 	gmtime_r(&data->tim, &then);
-	if (now.tm_sec == then.tm_sec)
-		return;
-	data->tim = t;
 
-	window_clock_draw_screen(wme);
-	wp->flags |= PANE_REDRAW;
+	if (now.tm_sec != then.tm_sec) {
+		data->tim = t;
+		window_clock_draw_screen(wme);
+		wp->flags |= PANE_REDRAW;
+	}
+
+	window_clock_start_timer(wme);
 }
 
 static struct screen *
@@ -157,13 +174,12 @@ window_clock_init(struct window_mode_entry *wme,
 	struct window_pane		*wp = wme->wp;
 	struct window_clock_mode_data	*data;
 	struct screen			*s;
-	struct timeval			 tv = { .tv_sec = 1 };
 
 	wme->data = data = xmalloc(sizeof *data);
 	data->tim = time(NULL);
 
 	evtimer_set(&data->timer, window_clock_timer_callback, wme);
-	evtimer_add(&data->timer, &tv);
+	window_clock_start_timer(wme);
 
 	s = &data->screen;
 	screen_init(s, screen_size_x(&wp->base), screen_size_y(&wp->base), 0);