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

--- ntp-4.2.6p5/ntpd/ntp_proto.c.delaycalib	2012-02-28 15:57:57.000000000 +0100

+++ ntp-4.2.6p5/ntpd/ntp_proto.c	2012-02-28 16:01:30.080135978 +0100

@@ -1514,7 +1514,7 @@ process_packet(

 		 */

 		if (FLAG_BC_VOL & peer->flags) {

 			peer->flags &= ~FLAG_BC_VOL;

-			peer->delay = (peer->offset - p_offset) * 2;

+			peer->delay = fabs(peer->offset - p_offset) * 2;

 		}

 		p_del = peer->delay;

 		p_offset += p_del / 2;