--- tftpd/src/srv.c	2014/02/20 23:05:58	1.2.2.9
+++ tftpd/src/srv.c	2014/02/20 23:11:18	1.2.2.10
@@ -355,8 +355,13 @@ ACK(sched_task_t *task)
 	if (ntohs(code) > cli.seq || (ntohs(code) < (cli.seq - 1))) {
 		code = htole16(5);
 		goto end;
-	} else if (ntohs(code) == cli.seq)
-		cli.seq++;
+	} else if (ntohs(code) == cli.seq) {
+		/* check for rollover seq id */
+		if (cli.roll && cli.seq == USHRT_MAX)
+			cli.seq = cli.roll;
+		else
+			cli.seq++;
+	}
 
 	EVERBOSE(3, "ACK:: seq=%hu; my new seq=%hu;", ntohs(code), cli.seq);