diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
index ff23cc1..70b9635 100644
--- a/sound/usb/usx2y/usb_stream.c
+++ b/sound/usb/usx2y/usb_stream.c
@@ -276,7 +276,8 @@
 	}
 }
 
-int usb_stream_prepare_playback(struct usb_stream_kernel *sk, struct urb *inurb)
+static int usb_stream_prepare_playback(struct usb_stream_kernel *sk,
+		struct urb *inurb)
 {
 	struct usb_stream *s = sk->s;
 	struct urb *io;