diff --git a/event-internal.h b/event-internal.h
index e52c129b..122195b3 100644
--- a/event-internal.h
+++ b/event-internal.h
@@ -262,6 +262,9 @@ struct event_base {
 	enum event_base_config_flag flags;
 
 	/* Notify main thread to wake up break, etc. */
+	/** True if the base already has a pending notify, and we don't need
+	 * to add any more. */
+	int is_notify_pending;
 	/** A socketpair used by some th_notify functions to wake up the main
 	 * thread. */
 	int th_notify_fd[2];
diff --git a/event.c b/event.c
index 0c8238d7..902aed54 100644
--- a/event.c
+++ b/event.c
@@ -1902,8 +1902,12 @@ evthread_notify_base_eventfd(struct event_base *base)
 static int
 evthread_notify_base(struct event_base *base)
 {
+	EVENT_BASE_ASSERT_LOCKED(base);
 	if (!base->th_notify_fn)
 		return -1;
+	if (base->is_notify_pending)
+		return 0;
+	base->is_notify_pending = 1;
 	return base->th_notify_fn(base);
 }
 
@@ -2247,8 +2251,6 @@ event_deferred_cb_schedule(struct deferred_cb_queue *queue,
 		cb->queued = 1;
 		TAILQ_INSERT_TAIL(&queue->deferred_cb_list, cb, cb_next);
 		++queue->active_count;
-		/* XXXX Can we get away with doing this only when adding
-		 * the first active deferred_cb to the queue? */
 		if (queue->notify_fn)
 			queue->notify_fn(queue, queue->notify_arg);
 	}
@@ -2594,11 +2596,15 @@ evthread_notify_drain_eventfd(evutil_socket_t fd, short what, void *arg)
 {
 	ev_uint64_t msg;
 	ev_ssize_t r;
+	struct event_base *base = arg;
 
 	r = read(fd, (void*) &msg, sizeof(msg));
 	if (r<0 && errno != EAGAIN) {
 		event_sock_warn(fd, "Error reading from eventfd");
 	}
+	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+	base->is_notify_pending = 0;
+	EVBASE_RELEASE_LOCK(base, th_base_lock);
 }
 #endif
 
@@ -2606,6 +2612,7 @@ static void
 evthread_notify_drain_default(evutil_socket_t fd, short what, void *arg)
 {
 	unsigned char buf[1024];
+	struct event_base *base = arg;
 #ifdef WIN32
 	while (recv(fd, (char*)buf, sizeof(buf), 0) > 0)
 		;
@@ -2613,6 +2620,10 @@ evthread_notify_drain_default(evutil_socket_t fd, short what, void *arg)
 	while (read(fd, (char*)buf, sizeof(buf)) > 0)
 		;
 #endif
+
+	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+	base->is_notify_pending = 0;
+	EVBASE_RELEASE_LOCK(base, th_base_lock);
 }
 
 int