diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c
index 0122930b14c7..0474e6638d21 100644
--- a/drivers/net/wireless/ath/carl9170/main.c
+++ b/drivers/net/wireless/ath/carl9170/main.c
@@ -1066,8 +1066,10 @@ static int carl9170_op_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	 * the high througput speed in 802.11n networks.
 	 */
 
-	if (!is_main_vif(ar, vif))
+	if (!is_main_vif(ar, vif)) {
+		mutex_lock(&ar->mutex);
 		goto err_softw;
+	}
 
 	/*
 	 * While the hardware supports *catch-all* key, for offloading