diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 1828225ba882a20921028462f0c83276fd1fcd27..c022c3ee227aeb750635e7445fb8221ac8397eff 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -513,9 +513,9 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	if (WARN_ON(!iface))
 		return -EINVAL;
 	alts = usb_altnum_to_altsetting(iface, fmt->altsetting);
-	altsd = get_iface_desc(alts);
-	if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting))
+	if (WARN_ON(!alts))
 		return -EINVAL;
+	altsd = get_iface_desc(alts);
 
 	if (fmt == subs->cur_audiofmt)
 		return 0;