diff --git a/net/mac80211/rate.c b/net/mac80211/rate.c
index 9857693b91ec721ff71e3f3cd1087ccc289912e1..9ce8883d5f449ed438f0a4a4a4807ede153c6725 100644
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -716,7 +716,7 @@ static bool rate_control_cap_mask(struct ieee80211_sub_if_data *sdata,
 
 		/* Filter out rates that the STA does not support */
 		*mask &= sta->supp_rates[sband->band];
-		for (i = 0; i < sizeof(mcs_mask); i++)
+		for (i = 0; i < IEEE80211_HT_MCS_MASK_LEN; i++)
 			mcs_mask[i] &= sta->ht_cap.mcs.rx_mask[i];
 
 		sta_vht_cap = sta->vht_cap.vht_mcs.rx_mcs_map;