diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
index bbb2fedacb25..119bd3582295 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mcu.c
@@ -51,7 +51,7 @@ mt7915_mcu_get_sta_nss(u16 mcs_map)
 			break;
 	}
 
-	return nss - 1;
+	return nss ? nss - 1 : 0;
 }
 
 static void