diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 0537c63..8e18f7e 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -204,6 +204,10 @@
 				    int index, char *buf, int maxlen)
 {
 	int len = usb_string(state->chip->dev, index, buf, maxlen - 1);
+
+	if (len < 0)
+		return 0;
+
 	buf[len] = 0;
 	return len;
 }