diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 9de4221de730..8b91be394407 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -377,7 +377,7 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 add_sync_ep_from_ifnum:
 	iface = usb_ifnum_to_if(dev, ifnum);
 
-	if (!iface || iface->num_altsetting == 0)
+	if (!iface || iface->num_altsetting < 2)
 		return -EINVAL;
 
 	alts = &iface->altsetting[1];