diff -up ntp-4.2.6p5/ntpd/ntp_proto.c.orig ntp-4.2.6p5/ntpd/ntp_proto.c

--- ntp-4.2.6p5/ntpd/ntp_proto.c.orig	2015-11-06 10:48:42.672684827 +0100

+++ ntp-4.2.6p5/ntpd/ntp_proto.c	2015-11-06 13:03:14.284092484 +0100

@@ -1069,7 +1069,7 @@ receive(

 	 * the packet is not bogus in symmetric interleaved mode.

 	 */

 	} else if (peer->flip == 0) {

-		if (!L_ISEQU(&p_org, &peer->aorg)) {

+		if (L_ISZERO(&p_org) || !L_ISEQU(&p_org, &peer->aorg)) {

 			peer->bogusorg++;

 			peer->flash |= TEST2;	/* bogus */

 			if (!L_ISZERO(&peer->dst) && L_ISEQU(&p_org,