diff --git a/mt7603_main.c b/mt7603_main.c
index 5af07e9e..fe43c85f 100644
--- a/mt7603_main.c
+++ b/mt7603_main.c
@@ -343,6 +343,17 @@ mt7603_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	struct mt76_wcid *wcid = msta ? &msta->wcid : &mvif->wcid;
 	int idx = key->keyidx;
 
+	/* fall back to sw encryption for unsupported ciphers */
+	switch (key->cipher) {
+	case WLAN_CIPHER_SUITE_WEP40:
+	case WLAN_CIPHER_SUITE_WEP104:
+	case WLAN_CIPHER_SUITE_TKIP:
+	case WLAN_CIPHER_SUITE_CCMP:
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
 	/*
 	 * The hardware does not support per-STA RX GTK, fall back
 	 * to software mode for these.