diff --git a/src/core/meta-idle-monitor.c b/src/core/meta-idle-monitor.c
index 00b6ddb8e..d351e65a9 100644
--- a/src/core/meta-idle-monitor.c
+++ b/src/core/meta-idle-monitor.c
@@ -74,7 +74,8 @@ typedef struct
   guint64                   timeout_msec;
 
   /* x11 */
-  XSyncAlarm	            xalarm;
+  XSyncAlarm                xalarm;
+  int                       idle_source_id;
 } MetaIdleMonitorWatch;
 
 enum
@@ -110,6 +111,12 @@ fire_watch (MetaIdleMonitorWatch *watch)
   monitor = watch->monitor;
   g_object_ref (monitor);
 
+  if (watch->idle_source_id)
+    {
+      g_source_remove (watch->idle_source_id);
+      watch->idle_source_id = 0;
+    }
+
   id = watch->id;
   is_user_active_watch = (watch->timeout_msec == 0);
 
@@ -281,6 +288,12 @@ idle_monitor_watch_free (MetaIdleMonitorWatch *watch)
 
   monitor = watch->monitor;
 
+  if (watch->idle_source_id)
+    {
+      g_source_remove (watch->idle_source_id);
+      watch->idle_source_id = 0;
+    }
+
   if (watch->notify != NULL)
     watch->notify (watch->user_data);
 
@@ -449,6 +462,17 @@ meta_idle_monitor_get_for_device (int device_id)
   return device_monitors[device_id];
 }
 
+static gboolean
+fire_watch_idle (gpointer data)
+{
+  MetaIdleMonitorWatch *watch = data;
+
+  watch->idle_source_id = 0;
+  fire_watch (watch);
+
+  return FALSE;
+}
+
 static MetaIdleMonitorWatch *
 make_watch (MetaIdleMonitor           *monitor,
             guint64                    timeout_msec,
@@ -471,6 +495,9 @@ make_watch (MetaIdleMonitor           *monitor,
       watch->xalarm = _xsync_alarm_set (monitor, XSyncPositiveTransition, timeout_msec, TRUE);
 
       g_hash_table_add (monitor->alarms, (gpointer) watch->xalarm);
+
+      if (meta_idle_monitor_get_idletime (monitor) > (gint64)timeout_msec)
+        watch->idle_source_id = g_idle_add (fire_watch_idle, watch);
     }
   else
     {