diff --git a/src/dunst.c b/src/dunst.c
index c76e078..2bf6899 100644
--- a/src/dunst.c
+++ b/src/dunst.c
@@ -19,6 +19,7 @@
 #include "option_parser.h"
 #include "queues.h"
 #include "settings.h"
+#include "utils.h"
 #include "x11/screen.h"
 #include "x11/x.h"
 
@@ -70,7 +71,7 @@ static gboolean run(void *data)
         }
 
         if (xctx.visible) {
-                gint64 now = g_get_monotonic_time();
+                gint64 now = time_monotonic_now();
                 gint64 sleep = queues_get_next_datachange(now);
                 gint64 timeout_at = now + sleep;
 
diff --git a/src/notification.c b/src/notification.c
index b54b79f..d3d8445 100644
--- a/src/notification.c
+++ b/src/notification.c
@@ -290,7 +290,7 @@ notification *notification_create(void)
         n->markup = settings.markup;
         n->format = settings.format;
 
-        n->timestamp = g_get_monotonic_time();
+        n->timestamp = time_monotonic_now();
 
         n->urgency = URG_NORM;
         n->timeout = -1;
@@ -528,7 +528,7 @@ void notification_update_text_to_render(notification *n)
 
         /* print age */
         gint64 hours, minutes, seconds;
-        gint64 t_delta = g_get_monotonic_time() - n->timestamp;
+        gint64 t_delta = time_monotonic_now() - n->timestamp;
 
         if (settings.show_age_threshold >= 0
             && t_delta >= settings.show_age_threshold) {
diff --git a/src/queues.c b/src/queues.c
index cf229a2..e64172d 100644
--- a/src/queues.c
+++ b/src/queues.c
@@ -23,6 +23,7 @@
 #include "log.h"
 #include "notification.h"
 #include "settings.h"
+#include "utils.h"
 
 /* notification lists */
 static GQueue *waiting   = NULL; /**< all new notifications get into here */
@@ -133,7 +134,7 @@ static bool queues_stack_duplicate(notification *n)
 
                         iter->data = n;
 
-                        n->start = g_get_monotonic_time();
+                        n->start = time_monotonic_now();
 
                         n->dup_count = orig->dup_count;
 
@@ -180,7 +181,7 @@ bool queues_notification_replace_id(notification *new)
                 notification *old = iter->data;
                 if (old->id == new->id) {
                         iter->data = new;
-                        new->start = g_get_monotonic_time();
+                        new->start = time_monotonic_now();
                         new->dup_count = old->dup_count;
                         notification_run_script(new);
                         notification_free(old);
@@ -305,7 +306,7 @@ void queues_check_timeouts(bool idle, bool fullscreen)
 
                 /* don't timeout when user is idle */
                 if (is_idle && !n->transient) {
-                        n->start = g_get_monotonic_time();
+                        n->start = time_monotonic_now();
                         continue;
                 }
 
@@ -315,7 +316,7 @@ void queues_check_timeouts(bool idle, bool fullscreen)
                 }
 
                 /* remove old message */
-                if (g_get_monotonic_time() - n->start > n->timeout) {
+                if (time_monotonic_now() - n->start > n->timeout) {
                         queues_notification_close(n, REASON_TIME);
                 }
         }
@@ -368,7 +369,7 @@ void queues_update(bool fullscreen)
                         continue;
                 }
 
-                n->start = g_get_monotonic_time();
+                n->start = time_monotonic_now();
 
                 if (!n->redisplayed && n->script) {
                         notification_run_script(n);
diff --git a/src/utils.c b/src/utils.c
index 8d2f00e..6eda3bc 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 
 #include "log.h"
 
@@ -166,4 +167,21 @@ gint64 string_to_time(const char *string)
                 return 0;
 }
 
+/* see utils.h */
+gint64 time_monotonic_now(void)
+{
+        struct timespec tv_now;
+
+        /* On Linux, BOOTTIME is the correct monotonic time,
+         * as BOOTTIME counts onwards during sleep. For all other
+         * POSIX compliant OSes, MONOTONIC should also count onwards
+         * during system sleep. */
+#ifdef __linux__
+        clock_gettime(CLOCK_BOOTTIME, &tv_now);
+#else
+        clock_gettime(CLOCK_MONOTONIC, &tv_now);
+#endif
+        return (gint64)tv_now.tv_sec  * G_USEC_PER_SEC
+                     + tv_now.tv_nsec / 1000;
+}
 /* vim: set tabstop=8 shiftwidth=8 expandtab textwidth=0: */
diff --git a/src/utils.h b/src/utils.h
index 874bb49..48ee618 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -27,5 +27,14 @@ char *string_to_path(char *string);
 /* convert time units (ms, s, m) to internal gint64 microseconds */
 gint64 string_to_time(const char *string);
 
+/**
+ * Get the current monotonic time. In contrast to `g_get_monotonic_time`,
+ * this function respects the real monotonic time of the system and
+ * counts onwards during system sleep.
+ *
+ * @returns: A `gint64` monotonic time representation
+ */
+gint64 time_monotonic_now(void);
+
 #endif
 /* vim: set tabstop=8 shiftwidth=8 expandtab textwidth=0: */