diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index db3eb21..6e66fff 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -36,6 +36,7 @@
 	struct snd_card *card;
 	u32 usb_id;
 	int shutdown;
+	struct mutex shutdown_mutex;
 	unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */
 	int num_interfaces;
 	int num_suspended_intf;