diff --git a/sys/dev/ath/if_ath.c b/sys/dev/ath/if_ath.c
index a5f0b3799599..3a401fefe723 100644
--- a/sys/dev/ath/if_ath.c
+++ b/sys/dev/ath/if_ath.c
@@ -130,7 +130,7 @@ static void	ath_start(struct ifnet *);
 static int	ath_reset(struct ifnet *);
 static int	ath_reset_vap(struct ieee80211vap *, u_long);
 static int	ath_media_change(struct ifnet *);
-static void	ath_watchdog(struct ifnet *);
+static void	ath_watchdog(void *);
 static int	ath_ioctl(struct ifnet *, u_long, caddr_t);
 static void	ath_fatal_proc(void *, int);
 static void	ath_bmiss_vap(struct ieee80211vap *);
@@ -458,7 +458,8 @@ ath_attach(u_int16_t devid, struct ath_softc *sc)
 		if_printf(ifp, "failed to allocate descriptors: %d\n", error);
 		goto bad;
 	}
-	callout_init(&sc->sc_cal_ch, CALLOUT_MPSAFE);
+	callout_init_mtx(&sc->sc_cal_ch, &sc->sc_mtx, 0);
+	callout_init_mtx(&sc->sc_wd_ch, &sc->sc_mtx, 0);
 
 	ATH_TXBUF_LOCK_INIT(sc);
 
@@ -567,7 +568,7 @@ ath_attach(u_int16_t devid, struct ath_softc *sc)
 	ifp->if_softc = sc;
 	ifp->if_flags = IFF_SIMPLEX | IFF_BROADCAST | IFF_MULTICAST;
 	ifp->if_start = ath_start;
-	ifp->if_watchdog = ath_watchdog;
+	ifp->if_watchdog = NULL;
 	ifp->if_ioctl = ath_ioctl;
 	ifp->if_init = ath_init;
 	IFQ_SET_MAXLEN(&ifp->if_snd, IFQ_MAXLEN);
@@ -1528,6 +1529,7 @@ ath_init(void *arg)
 		sc->sc_imask |= HAL_INT_MIB;
 
 	ifp->if_drv_flags |= IFF_DRV_RUNNING;
+	callout_reset(&sc->sc_wd_ch, hz, ath_watchdog, sc);
 	ath_hal_intrset(ah, sc->sc_imask);
 
 	ATH_UNLOCK(sc);
@@ -1570,8 +1572,9 @@ ath_stop_locked(struct ifnet *ifp)
 		if (sc->sc_tx99 != NULL)
 			sc->sc_tx99->stop(sc->sc_tx99);
 #endif
+		callout_stop(&sc->sc_wd_ch);
+		sc->sc_wd_timer = 0;
 		ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
-		ifp->if_timer = 0;
 		if (!sc->sc_invalid) {
 			if (sc->sc_softled) {
 				callout_stop(&sc->sc_ledtimer);
@@ -2195,7 +2198,7 @@ ath_start(struct ifnet *ifp)
 			goto nextfrag;
 		}
 
-		ifp->if_timer = 5;
+		sc->sc_wd_timer = 5;
 #if 0
 		/*
 		 * Flush stale frames from the fast-frame staging queue.
@@ -5372,7 +5375,7 @@ ath_tx_proc_q0(void *arg, int npending)
 	if (txqactive(sc->sc_ah, sc->sc_cabq->axq_qnum))
 		ath_tx_processq(sc, sc->sc_cabq);
 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
-	ifp->if_timer = 0;
+	sc->sc_wd_timer = 0;
 
 	if (sc->sc_softled)
 		ath_led_event(sc, sc->sc_txrix);
@@ -5409,7 +5412,7 @@ ath_tx_proc_q0123(void *arg, int npending)
 		sc->sc_lastrx = ath_hal_gettsf64(sc->sc_ah);
 
 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
-	ifp->if_timer = 0;
+	sc->sc_wd_timer = 0;
 
 	if (sc->sc_softled)
 		ath_led_event(sc, sc->sc_txrix);
@@ -5438,7 +5441,7 @@ ath_tx_proc(void *arg, int npending)
 		sc->sc_lastrx = ath_hal_gettsf64(sc->sc_ah);
 
 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
-	ifp->if_timer = 0;
+	sc->sc_wd_timer = 0;
 
 	if (sc->sc_softled)
 		ath_led_event(sc, sc->sc_txrix);
@@ -5557,7 +5560,7 @@ ath_draintxq(struct ath_softc *sc)
 	}
 #endif /* ATH_DEBUG */
 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
-	ifp->if_timer = 0;
+	sc->sc_wd_timer = 0;
 }
 
 /*
@@ -5902,7 +5905,7 @@ ath_newstate(struct ieee80211vap *vap, enum ieee80211_state nstate, int arg)
 		ieee80211_state_name[vap->iv_state],
 		ieee80211_state_name[nstate]);
 
-	callout_stop(&sc->sc_cal_ch);
+	callout_drain(&sc->sc_cal_ch);
 	ath_hal_setledstate(ah, leds[nstate]);	/* set LED */
 
 	if (nstate == IEEE80211_S_SCAN) {
@@ -6436,11 +6439,12 @@ ath_printtxbuf(struct ath_softc *sc, const struct ath_buf *bf,
 #endif /* ATH_DEBUG */
 
 static void
-ath_watchdog(struct ifnet *ifp)
+ath_watchdog(void *arg)
 {
-	struct ath_softc *sc = ifp->if_softc;
+	struct ath_softc *sc = arg;
 
-	if ((ifp->if_drv_flags & IFF_DRV_RUNNING) && !sc->sc_invalid) {
+	if (sc->sc_wd_timer != 0 && --sc->sc_wd_timer == 0) {
+		struct ifnet *ifp = sc->sc_ifp;
 		uint32_t hangs;
 
 		if (ath_hal_gethangstate(sc->sc_ah, 0xffff, &hangs) &&
@@ -6453,6 +6457,7 @@ ath_watchdog(struct ifnet *ifp)
 		ifp->if_oerrors++;
 		sc->sc_stats.ast_watchdog++;
 	}
+	callout_schedule(&sc->sc_wd_ch, hz);
 }
 
 #ifdef ATH_DIAGAPI
@@ -7272,7 +7277,7 @@ ath_raw_xmit(struct ieee80211_node *ni, struct mbuf *m,
 		if (ath_tx_raw_start(sc, ni, bf, m, params))
 			goto bad;
 	}
-	ifp->if_timer = 5;
+	sc->sc_wd_timer = 5;
 
 	return 0;
 bad:
diff --git a/sys/dev/ath/if_athvar.h b/sys/dev/ath/if_athvar.h
index 2640ef2f8345..540b76a6bbd2 100644
--- a/sys/dev/ath/if_athvar.h
+++ b/sys/dev/ath/if_athvar.h
@@ -321,6 +321,8 @@ struct ath_softc {
 	struct ath_txq		sc_txq[HAL_NUM_TX_QUEUES];
 	struct ath_txq		*sc_ac2q[5];	/* WME AC -> h/w q map */ 
 	struct task		sc_txtask;	/* tx int processing */
+	int			sc_wd_timer;	/* count down for wd timer */
+	struct callout		sc_wd_ch;	/* tx watchdog timer */
 
 	struct ath_descdma	sc_bdma;	/* beacon descriptors */
 	ath_bufhead		sc_bbuf;	/* beacon buffers */