diff --git a/sound/drivers/mts64.c b/sound/drivers/mts64.c
index 36e9eab204ca..cefaa00b83e7 100644
--- a/sound/drivers/mts64.c
+++ b/sound/drivers/mts64.c
@@ -900,6 +900,12 @@ static int snd_mts64_probe(struct platform_device *pdev)
 	p = platform_get_drvdata(pdev);
 	platform_set_drvdata(pdev, NULL);
 
+	if (dev < 0) {
+		dev_warn(&pdev->dev,
+			 "Invalid card index %d, using default 0\n", dev);
+		dev = 0;
+	}
+
 	if (dev >= SNDRV_CARDS)
 		return -ENODEV;
 	if (!enable[dev])