diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 8d426f637f58..7486f2dab4ba 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1672,11 +1672,15 @@ __ieee80211_sta_handle_tspec_ac_params(struct ieee80211_sub_if_data *sdata)
 			     non_acm_ac++)
 				if (!(sdata->wmm_acm & BIT(7 - 2 * non_acm_ac)))
 					break;
-			/* The loop will result in using BK even if it requires
-			 * admission control, such configuration makes no sense
-			 * and we have to transmit somehow - the AC selection
-			 * does the same thing.
+			/* Usually the loop will result in using BK even if it
+			 * requires admission control, but such a configuration
+			 * makes no sense and we have to transmit somehow - the
+			 * AC selection does the same thing.
+			 * If we started out trying to downgrade from BK, then
+			 * the extra condition here might be needed.
 			 */
+			if (non_acm_ac >= IEEE80211_NUM_ACS)
+				non_acm_ac = IEEE80211_AC_BK;
 			if (drv_conf_tx(local, sdata, ac,
 					&sdata->tx_conf[non_acm_ac]))
 				sdata_err(sdata,