diff --git a/sched.c b/sched.c
index 3c5dc11..559c4a2 100644
--- a/sched.c
+++ b/sched.c
@@ -65,6 +65,12 @@ static ARR_Instance file_handlers;
 static struct timespec last_select_ts, last_select_ts_raw;
 static double last_select_ts_err;
 
+#define TS_MONO_PRECISION_NS 10000000U
+
+/* Monotonic low-precision timestamp measuring interval since the start */
+static double last_select_ts_mono;
+static uint32_t last_select_ts_mono_ns;
+
 /* ================================================== */
 
 /* Variables to handler the timer queue */
@@ -136,6 +142,8 @@ SCH_Initialise(void)
 
   LCL_ReadRawTime(&last_select_ts_raw);
   last_select_ts = last_select_ts_raw;
+  last_select_ts_mono = 0.0;
+  last_select_ts_mono_ns = 0;
 
   initialised = 1;
 }
@@ -249,6 +257,14 @@ SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw)
 
 /* ================================================== */
 
+double
+SCH_GetLastEventMonoTime(void)
+{
+  return last_select_ts_mono;
+}
+
+/* ================================================== */
+
 #define TQE_ALLOC_QUANTUM 32
 
 static TimerQueueEntry *
@@ -722,6 +738,31 @@ check_current_time(struct timespec *prev_raw, struct timespec *raw, int timeout,
 
 /* ================================================== */
 
+static void
+update_monotonic_time(struct timespec *now, struct timespec *before)
+{
+  struct timespec diff;
+
+  /* Avoid frequent floating-point operations and handle small
+     increments to a large value */
+
+  UTI_DiffTimespecs(&diff, now, before);
+  if (diff.tv_sec == 0) {
+    last_select_ts_mono_ns += diff.tv_nsec;
+  } else {
+    last_select_ts_mono += fabs(UTI_TimespecToDouble(&diff) +
+                                last_select_ts_mono_ns / 1.0e9);
+    last_select_ts_mono_ns = 0;
+  }
+
+  if (last_select_ts_mono_ns > TS_MONO_PRECISION_NS) {
+    last_select_ts_mono += last_select_ts_mono_ns / 1.0e9;
+    last_select_ts_mono_ns = 0;
+  }
+}
+
+/* ================================================== */
+
 void
 SCH_MainLoop(void)
 {
@@ -778,6 +819,8 @@ SCH_MainLoop(void)
       LCL_CookTime(&now, &cooked, &err);
     }
 
+    update_monotonic_time(&cooked, &last_select_ts);
+
     last_select_ts_raw = now;
     last_select_ts = cooked;
     last_select_ts_err = err;
diff --git a/sched.h b/sched.h
index b7d4279..0d3b311 100644
--- a/sched.h
+++ b/sched.h
@@ -65,6 +65,9 @@ extern void SCH_SetFileHandlerEvent(int fd, int event, int enable);
 /* Get the time stamp taken after a file descriptor became ready or a timeout expired */
 extern void SCH_GetLastEventTime(struct timespec *cooked, double *err, struct timespec *raw);
 
+/* Get a low-precision monotonic timestamp (starting at 0.0) */
+extern double SCH_GetLastEventMonoTime(void);
+
 /* This queues a timeout to elapse at a given (raw) local time */
 extern SCH_TimeoutID SCH_AddTimeout(struct timespec *ts, SCH_TimeoutHandler handler, SCH_ArbitraryArgument arg);