diff --git a/tty.c b/tty.c
index 6e413572..5325f38c 100644
--- a/tty.c
+++ b/tty.c
@@ -628,7 +628,8 @@ tty_add(struct tty *tty, const char *buf, size_t len)
 
 	if (tty_log_fd != -1)
 		write(tty_log_fd, buf, len);
-	if (tty->flags & TTY_STARTED)
+	if ((tty->flags & TTY_STARTED) &&
+	    !event_pending(&tty->event_out, EV_WRITE, NULL))
 		event_add(&tty->event_out, NULL);
 }