diff --git a/sys/dev/ath/ath_rate/sample/sample.c b/sys/dev/ath/ath_rate/sample/sample.c
--- a/sys/dev/ath/ath_rate/sample/sample.c
+++ b/sys/dev/ath/ath_rate/sample/sample.c
@@ -857,7 +857,8 @@
 			 */
 			if (rt->info[best_rix].phy == IEEE80211_T_HT)
 				ieee80211_node_set_txrate_ht_mcsrate(
-				    &an->an_node, MCS(best_rix));
+				    &an->an_node,
+				    MCS(best_rix) & IEEE80211_RATE_VAL);
 			else
 				ieee80211_node_set_txrate_dot11rate(
 				    &an->an_node,