diff --git a/mt76x2_init.c b/mt76x2_init.c
index 4268e2bf3..35f06aba3 100644
--- a/mt76x2_init.c
+++ b/mt76x2_init.c
@@ -492,7 +492,10 @@ void mt76x2_set_tx_ackto(struct mt76x2_dev *dev)
 {
 	u8 ackto, sifs, slottime = dev->slottime;
 
+	/* As defined by IEEE 802.11-2007 17.3.8.6 */
 	slottime += 3 * dev->coverage_class;
+	mt76_rmw_field(dev, MT_BKOFF_SLOT_CFG,
+		       MT_BKOFF_SLOT_CFG_SLOTTIME, slottime);
 
 	sifs = mt76_get_field(dev, MT_XIFS_TIME_CFG,
 			      MT_XIFS_TIME_CFG_OFDM_SIFS);
diff --git a/mt76x2_main.c b/mt76x2_main.c
index 5c0d1e126..826c2431e 100644
--- a/mt76x2_main.c
+++ b/mt76x2_main.c
@@ -247,8 +247,7 @@ mt76x2_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		int slottime = info->use_short_slot ? 9 : 20;
 
 		dev->slottime = slottime;
-		mt76_rmw_field(dev, MT_BKOFF_SLOT_CFG,
-			       MT_BKOFF_SLOT_CFG_SLOTTIME, slottime);
+		mt76x2_set_tx_ackto(dev);
 	}
 
 	mutex_unlock(&dev->mutex);