diff --git a/event.c b/event.c
index 746ed0ba3..d1d885c1e 100644
--- a/event.c
+++ b/event.c
@@ -2573,7 +2573,7 @@ static int
 evthread_notify_base_default(struct event_base *base)
 {
 	char buf[1];
-	int r;
+	ev_ssize_t r;
 	buf[0] = (char) 0;
 #ifdef _WIN32
 	r = send(base->th_notify_fd[1], buf, 1, 0);