diff --git a/mt7921/main.c b/mt7921/main.c
index bb7c986f..b4eac59c 100644
--- a/mt7921/main.c
+++ b/mt7921/main.c
@@ -750,6 +750,7 @@ void mt7921_mac_sta_assoc(struct mt76_dev *mdev, struct ieee80211_vif *vif,
 
 	mt7921_mac_wtbl_update(dev, msta->wcid.idx,
 			       MT_WTBL_UPDATE_ADM_COUNT_CLEAR);
+	memset(msta->airtime_ac, 0, sizeof(msta->airtime_ac));
 
 	mt7921_mcu_sta_update(dev, sta, vif, true, MT76_STA_INFO_STATE_ASSOC);