diff --git a/drivers/net/wireless/mediatek/mt76/mt76x0/tx.c b/drivers/net/wireless/mediatek/mt76/mt76x0/tx.c
index 751b49c28ae5..c45d05d5aab1 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x0/tx.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x0/tx.c
@@ -166,7 +166,7 @@ void mt76x0_tx(struct ieee80211_hw *hw, struct ieee80211_tx_control *control,
 	if (sta) {
 		msta = (struct mt76_sta *) sta->drv_priv;
 		wcid = &msta->wcid;
-	} else if (vif && (!info->control.hw_key && wcid->hw_key_idx != -1)) {
+	} else if (vif && (!info->control.hw_key && wcid->hw_key_idx != 0xff)) {
 		struct mt76_vif *mvif = (struct mt76_vif *)vif->drv_priv;
 
 		wcid = &mvif->group_wcid;
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_tx_common.c b/drivers/net/wireless/mediatek/mt76/mt76x2_tx_common.c
index 36afb166fa3f..c0ca0df84ed8 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_tx_common.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_tx_common.c
@@ -32,7 +32,7 @@ void mt76x2_tx(struct ieee80211_hw *hw, struct ieee80211_tx_control *control,
 		msta = (struct mt76x2_sta *)control->sta->drv_priv;
 		wcid = &msta->wcid;
 		/* sw encrypted frames */
-		if (!info->control.hw_key && wcid->hw_key_idx != -1)
+		if (!info->control.hw_key && wcid->hw_key_idx != 0xff)
 			control->sta = NULL;
 	}