diff --git a/sys/dev/ic/atw.c b/sys/dev/ic/atw.c
index 753b5954765b..b981a28f3fc1 100644
--- a/sys/dev/ic/atw.c
+++ b/sys/dev/ic/atw.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: atw.c,v 1.80 2004/10/30 18:08:36 thorpej Exp $	*/
+/*	$NetBSD: atw.c,v 1.81 2004/12/27 01:51:49 mycroft Exp $	*/
 
 /*-
  * Copyright (c) 1998, 1999, 2000, 2002, 2003, 2004 The NetBSD Foundation, Inc.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: atw.c,v 1.80 2004/10/30 18:08:36 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: atw.c,v 1.81 2004/12/27 01:51:49 mycroft Exp $");
 
 #include "bpfilter.h"
 
@@ -3539,7 +3539,7 @@ atw_start(struct ifnet *ifp)
 		 * probably strip FCS just in case it sticks around in
 		 * bridged packets.
 		 */
-		hh->atw_service = IEEE80211_PLCP_SERVICE; /* XXX guess */
+		hh->atw_service = 0x00; /* XXX guess */
 		hh->atw_paylen = htole16(m0->m_pkthdr.len -
 		    sizeof(struct atw_frame));
 
diff --git a/sys/dev/ic/rtw.c b/sys/dev/ic/rtw.c
index c6bf913193bf..8e5238ad009e 100644
--- a/sys/dev/ic/rtw.c
+++ b/sys/dev/ic/rtw.c
@@ -1,4 +1,4 @@
-/* $NetBSD: rtw.c,v 1.24 2004/12/26 22:59:41 dyoung Exp $ */
+/* $NetBSD: rtw.c,v 1.25 2004/12/27 01:51:49 mycroft Exp $ */
 /*-
  * Copyright (c) 2004, 2005 David Young.  All rights reserved.
  *
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rtw.c,v 1.24 2004/12/26 22:59:41 dyoung Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rtw.c,v 1.25 2004/12/27 01:51:49 mycroft Exp $");
 
 #include "bpfilter.h"
 
@@ -2740,7 +2740,7 @@ rtw_start(struct ifnet *ifp)
 		ctl1 = LSHIFT(d0->d_plcp_len, RTW_TXCTL1_LENGTH_MASK) |
 		    LSHIFT(d0->d_rts_dur, RTW_TXCTL1_RTSDUR_MASK);
 
-		if ((d0->d_plcp_svc & IEEE80211_PLCP_SERVICE_LENEXT) != 0)
+		if (d0->d_residue)
 			ctl1 |= RTW_TXCTL1_LENGEXT;
 
 		/* TBD fragmentation */
diff --git a/sys/net80211/ieee80211.h b/sys/net80211/ieee80211.h
index b10bea933d69..85e228bd238a 100644
--- a/sys/net80211/ieee80211.h
+++ b/sys/net80211/ieee80211.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: ieee80211.h,v 1.9 2004/12/23 05:25:41 dyoung Exp $	*/
+/*	$NetBSD: ieee80211.h,v 1.10 2004/12/27 01:51:49 mycroft Exp $	*/
 /*-
  * Copyright (c) 2001 Atsushi Onoe
  * Copyright (c) 2002-2004 Sam Leffler, Errno Consulting
@@ -53,9 +53,6 @@ struct ieee80211_plcp_hdr {
 } __attribute__((__packed__));
 
 #define IEEE80211_PLCP_SFD      0xF3A0 
-#define IEEE80211_PLCP_SERVICE  0x00
-#define IEEE80211_PLCP_SERVICE_PBCC  0x08	/* PBCC encoded */
-#define IEEE80211_PLCP_SERVICE_LENEXT  0x80	/* length extension bit */
 
 /*
  * generic definitions for IEEE 802.11 frames
@@ -614,7 +611,7 @@ struct ieee80211_duration {
 	uint16_t	d_rts_dur;
 	uint16_t	d_data_dur;
 	uint16_t	d_plcp_len;
-	uint8_t		d_plcp_svc;
+	uint8_t		d_residue;	/* unused octets in time slot */
 };
 
 /* One Time Unit (TU) is 1Kus = 1024 microseconds. */
diff --git a/sys/net80211/ieee80211_output.c b/sys/net80211/ieee80211_output.c
index 7e61e18bed30..48faf64bf3d2 100644
--- a/sys/net80211/ieee80211_output.c
+++ b/sys/net80211/ieee80211_output.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: ieee80211_output.c,v 1.19 2004/12/23 06:08:52 dyoung Exp $	*/
+/*	$NetBSD: ieee80211_output.c,v 1.20 2004/12/27 01:51:49 mycroft Exp $	*/
 /*-
  * Copyright (c) 2001 Atsushi Onoe
  * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
@@ -35,7 +35,7 @@
 #ifdef __FreeBSD__
 __FBSDID("$FreeBSD: src/sys/net80211/ieee80211_output.c,v 1.10 2004/04/02 23:25:39 sam Exp $");
 #else
-__KERNEL_RCSID(0, "$NetBSD: ieee80211_output.c,v 1.19 2004/12/23 06:08:52 dyoung Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ieee80211_output.c,v 1.20 2004/12/27 01:51:49 mycroft Exp $");
 #endif
 
 #include "opt_inet.h"
@@ -308,31 +308,24 @@ ieee80211_compute_duration1(int len, uint32_t flags, int rate,
 	/* RTS is always sent at 1 Mb/s.  (XXX Really?) */
 	d->d_rts_plcp_len = sizeof(struct ieee80211_frame_rts) * 8;
 #endif
-	d->d_plcp_svc = 0;
+	d->d_residue = 0;
+	data_dur = (bitlen * 2) / rate;
 
 	switch (rate) {
 	case 2:		/* 1 Mb/s */
 	case 4:		/* 2 Mb/s */
-		data_dur = (bitlen * 2) / rate;
-
 		/* 1 - 2 Mb/s WLAN: send ACK/CTS at 1 Mb/s */
 		cts = IEEE80211_DUR_DS_SLOW_CTS;
 		ack = IEEE80211_DUR_DS_SLOW_ACK;
 		break;
-	case 44:	/* 22  Mb/s */
-		d->d_plcp_svc = IEEE80211_PLCP_SERVICE_PBCC;
-		/*FALLTHROUGH*/
 	case 11:	/* 5.5 Mb/s */
 	case 22:	/* 11  Mb/s */
+	case 44:	/* 22  Mb/s */
 		remainder = (bitlen * 2) % rate;
-
-		if (remainder != 0)
-			data_dur = (bitlen * 2) / rate + 1;
-		else
-			data_dur = (bitlen * 2) / rate;
-
-		if (rate == 22 && remainder <= 6)
-			d->d_plcp_svc |= IEEE80211_PLCP_SERVICE_LENEXT;
+		if (remainder != 0) {
+			data_dur++;
+			d->d_residue = (rate - remainder) / 16;
+		}
 
 		/* 5.5 - 11 Mb/s WLAN: send ACK/CTS at 2 Mb/s */
 		cts = IEEE80211_DUR_DS_FAST_CTS;