diff --git a/pinger.c b/pinger.c
index 3f533ae6..d8f110ac 100644
--- a/pinger.c
+++ b/pinger.c
@@ -8,7 +8,7 @@
 struct pinger_tag {
     int interval;
     int pending;
-    unsigned long next;
+    unsigned long when_set, next;
     Backend *back;
     void *backhandle;
 };
@@ -28,7 +28,7 @@ static void pinger_timer(void *ctx, unsigned long now)
 
 static void pinger_schedule(Pinger pinger)
 {
-    int next;
+    unsigned long next;
 
     if (!pinger->interval) {
 	pinger->pending = FALSE;       /* cancel any pending ping */
@@ -37,8 +37,10 @@ static void pinger_schedule(Pinger pinger)
 
     next = schedule_timer(pinger->interval * TICKSPERSEC,
 			  pinger_timer, pinger);
-    if (!pinger->pending || next < pinger->next) {
+    if (!pinger->pending ||
+        (next - pinger->when_set) < (pinger->next - pinger->when_set)) {
 	pinger->next = next;
+        pinger->when_set = timing_last_clock();
 	pinger->pending = TRUE;
     }
 }
diff --git a/putty.h b/putty.h
index 73bfd9e4..a149edb1 100644
--- a/putty.h
+++ b/putty.h
@@ -1450,6 +1450,7 @@ unsigned long schedule_timer(int ticks, timer_fn_t fn, void *ctx);
 void expire_timer_context(void *ctx);
 int run_timers(unsigned long now, unsigned long *next);
 void timer_change_notify(unsigned long next);
+unsigned long timing_last_clock(void);
 
 /*
  * Exports from callback.c.
diff --git a/timing.c b/timing.c
index ccd76cd6..696c1e1d 100644
--- a/timing.c
+++ b/timing.c
@@ -148,6 +148,17 @@ unsigned long schedule_timer(int ticks, timer_fn_t fn, void *ctx)
     return when;
 }
 
+unsigned long timing_last_clock(void)
+{
+    /*
+     * Return the last value we stored in 'now'. In particular,
+     * calling this just after schedule_timer returns the value of
+     * 'now' that was used to decide when the timer you just set would
+     * go off.
+     */
+    return now;
+}
+
 /*
  * Call to run any timers whose time has reached the present.
  * Returns the time (in ticks) expected until the next timer after