diff --git a/sys/compat/linuxkpi/common/src/linux_80211.c b/sys/compat/linuxkpi/common/src/linux_80211.c
--- a/sys/compat/linuxkpi/common/src/linux_80211.c
+++ b/sys/compat/linuxkpi/common/src/linux_80211.c
@@ -5943,7 +5943,6 @@
 	}
 
 	if (ni != NULL) {
-		int ridx __unused;
 #ifdef LINUXKPI_DEBUG_80211
 		int old_rate;
 
@@ -5968,15 +5967,15 @@
 
 		IMPROVE("only update of rate matches but that requires us to get a proper rate");
 		ieee80211_ratectl_tx_complete(ni, &txs);
-		ridx = ieee80211_ratectl_rate(ni->ni_vap->iv_bss, NULL, 0);
+		(void) ieee80211_ratectl_rate(ni->ni_vap->iv_bss, NULL, 0);
 
 #ifdef LINUXKPI_DEBUG_80211
 		if (linuxkpi_debug_80211 & D80211_TRACE_TX) {
-			printf("TX-RATE: %s: old %d new %d ridx %d, "
+			printf("TX-RATE: %s: old %d new %d "
 			    "long_retries %d\n", __func__,
 			    old_rate,
 			    ieee80211_node_get_txrate_dot11rate(ni->ni_vap->iv_bss),
-			    ridx, txs.long_retries);
+			    txs.long_retries);
 		}
 #endif
 	}
diff --git a/sys/dev/bwi/if_bwi.c b/sys/dev/bwi/if_bwi.c
--- a/sys/dev/bwi/if_bwi.c
+++ b/sys/dev/bwi/if_bwi.c
@@ -2916,7 +2916,7 @@
 	uint32_t mac_ctrl;
 	uint16_t phy_ctrl;
 	bus_addr_t paddr;
-	int type, ismcast, pkt_len, error, rix;
+	int type, ismcast, pkt_len, error;
 #if 0
 	const uint8_t *p;
 	int i;
@@ -2943,15 +2943,10 @@
 	} else if (tp->ucastrate != IEEE80211_FIXED_RATE_NONE) {
 		rate = rate_fb = tp->ucastrate;
 	} else {
-		rix = ieee80211_ratectl_rate(ni, NULL, pkt_len);
+		ieee80211_ratectl_rate(ni, NULL, pkt_len);
 		rate = ieee80211_node_get_txrate_dot11rate(ni);
-
-		if (rix > 0) {
-			rate_fb = ni->ni_rates.rs_rates[rix-1] &
-				  IEEE80211_RATE_VAL;
-		} else {
-			rate_fb = rate;
-		}
+		/* TODO: assign rate_fb the previous rate, if available */
+		rate_fb = rate;
 	}
 	tb->tb_rate[0] = rate;
 	tb->tb_rate[1] = rate_fb;
diff --git a/sys/dev/bwn/if_bwn.c b/sys/dev/bwn/if_bwn.c
--- a/sys/dev/bwn/if_bwn.c
+++ b/sys/dev/bwn/if_bwn.c
@@ -6394,7 +6394,7 @@
 	uint8_t *prot_ptr;
 	unsigned int len;
 	uint32_t macctl = 0;
-	int rts_rate, rts_rate_fb, ismcast, isshort, rix, type;
+	int rts_rate, rts_rate_fb, ismcast, isshort, type;
 	uint16_t phyctl = 0;
 	uint8_t rate, rate_fb;
 	int fill_phy_ctl1 = 0;
@@ -6420,14 +6420,10 @@
 	else if (tp->ucastrate != IEEE80211_FIXED_RATE_NONE)
 		rate = rate_fb = tp->ucastrate;
 	else {
-		rix = ieee80211_ratectl_rate(ni, NULL, 0);
+		ieee80211_ratectl_rate(ni, NULL, 0);
 		rate = ieee80211_node_get_txrate_dot11rate(ni);
-
-		if (rix > 0)
-			rate_fb = ni->ni_rates.rs_rates[rix - 1] &
-			    IEEE80211_RATE_VAL;
-		else
-			rate_fb = rate;
+		/* TODO: assign rate_fb the previous rate, if available */
+		rate_fb = rate;
 	}
 
 	sc->sc_tx_rate = rate;
diff --git a/sys/dev/iwm/if_iwm.c b/sys/dev/iwm/if_iwm.c
--- a/sys/dev/iwm/if_iwm.c
+++ b/sys/dev/iwm/if_iwm.c
@@ -3503,11 +3503,11 @@
 	if (rate_matched) {
 		ieee80211_ratectl_tx_complete(ni, txs);
 
-		int rix = ieee80211_ratectl_rate(vap->iv_bss, NULL, 0);
+		ieee80211_ratectl_rate(vap->iv_bss, NULL, 0);
 		new_rate = ieee80211_node_get_txrate_dot11rate(vap->iv_bss);
 		if (new_rate != 0 && new_rate != cur_rate) {
 			struct iwm_node *in = IWM_NODE(vap->iv_bss);
-			iwm_setrates(sc, in, rix);
+			iwm_setrates(sc, in, new_rate);
 			iwm_send_lq_cmd(sc, &in->in_lq, FALSE);
 		}
  	}
@@ -4271,16 +4271,31 @@
 
 
 static void
-iwm_setrates(struct iwm_softc *sc, struct iwm_node *in, int rix)
+iwm_setrates(struct iwm_softc *sc, struct iwm_node *in, int dot11rate)
 {
+	struct ieee80211com *ic = &sc->sc_ic;
 	struct ieee80211_node *ni = &in->in_ni;
 	struct iwm_lq_cmd *lq = &in->in_lq;
 	struct ieee80211_rateset *rs = &ni->ni_rates;
 	int nrates = rs->rs_nrates;
 	int i, ridx, tab = 0;
 //	int txant = 0;
+	int rix;
 
-	KASSERT(rix >= 0 && rix < nrates, ("invalid rix"));
+	/*
+	 * Look up the rate index for the given legacy rate.
+	 *
+	 * This code path isn't currently looking at the ni_htrates
+	 * array for setting MCS rates.  It also doesn't have
+	 * any knowledge of VHT rates.
+	 */
+	rix = ieee80211_legacy_rate_lookup(ic->ic_rt, dot11rate);
+	if (rix < 0) {
+		device_printf(sc->sc_dev,
+		    "%s: failed to lookup dot11rate (%d)\n",
+		    __func__, dot11rate);
+		rix = 0;
+	}
 
 	if (nrates > nitems(lq->rs_table)) {
 		device_printf(sc->sc_dev,
@@ -4560,8 +4575,9 @@
 		iwm_enable_beacon_filter(sc, ivp);
 		iwm_power_update_mac(sc);
 		iwm_update_quotas(sc, ivp);
-		int rix = ieee80211_ratectl_rate(&in->in_ni, NULL, 0);
-		iwm_setrates(sc, in, rix);
+		ieee80211_ratectl_rate(&in->in_ni, NULL, 0);
+		int dot11rate = ieee80211_node_get_txrate_dot11rate(&in->in_ni);
+		iwm_setrates(sc, in, dot11rate);
 
 		if ((error = iwm_send_lq_cmd(sc, &in->in_lq, TRUE)) != 0) {
 			device_printf(sc->sc_dev,
diff --git a/sys/net80211/ieee80211_ratectl.h b/sys/net80211/ieee80211_ratectl.h
--- a/sys/net80211/ieee80211_ratectl.h
+++ b/sys/net80211/ieee80211_ratectl.h
@@ -127,12 +127,12 @@
 	vap->iv_rate->ir_node_deinit(ni);
 }
 
-static int __inline
+static void __inline
 ieee80211_ratectl_rate(struct ieee80211_node *ni, void *arg, uint32_t iarg)
 {
 	const struct ieee80211vap *vap = ni->ni_vap;
 
-	return vap->iv_rate->ir_rate(ni, arg, iarg);
+	(void) vap->iv_rate->ir_rate(ni, arg, iarg);
 }
 
 static __inline void