diff --git a/mt7615/main.c b/mt7615/main.c
index a4a9f1e1..9e254610 100644
--- a/mt7615/main.c
+++ b/mt7615/main.c
@@ -433,11 +433,17 @@ mt7615_conf_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif, u16 queue,
 {
 	struct mt7615_vif *mvif = (struct mt7615_vif *)vif->drv_priv;
 	struct mt7615_dev *dev = mt7615_hw_dev(hw);
+	int err;
+
+	mt7615_mutex_acquire(dev);
 
 	queue = mt7615_lmac_mapping(dev, queue);
 	queue += mvif->wmm_idx * MT7615_MAX_WMM_SETS;
+	err = mt7615_mcu_set_wmm(dev, queue, params);
 
-	return mt7615_mcu_set_wmm(dev, queue, params);
+	mt7615_mutex_release(dev);
+
+	return err;
 }
 
 static void mt7615_configure_filter(struct ieee80211_hw *hw,