diff --git a/sys/net80211/ieee80211_ht.c b/sys/net80211/ieee80211_ht.c
--- a/sys/net80211/ieee80211_ht.c
+++ b/sys/net80211/ieee80211_ht.c
@@ -2595,11 +2595,15 @@
 
 static int
 ht_recv_action_ht_txchwidth(struct ieee80211_node *ni,
-	const struct ieee80211_frame *wh,
-	const uint8_t *frm, const uint8_t *efrm)
+	const struct ieee80211_frame *wh __unused,
+	const uint8_t *frm, const uint8_t *efrm __unused)
 {
 	int chw;
 
+	/* If 20/40 is not supported the chw cannot change. */
+	if ((ni->ni_htcap & IEEE80211_HTCAP_CHWIDTH40) == 0)
+		return (0);
+
 	chw = (frm[2] == IEEE80211_A_HT_TXCHWIDTH_2040) ?
 	    IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;