diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
index f604846ec6e6..e8619bb74358 100644
--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -212,6 +212,8 @@ int snd_usb_caiaq_send_command(struct snd_usb_caiaqdev *cdev,
 	if (len > EP1_BUFSIZE - 1)
 		len = EP1_BUFSIZE - 1;
 
+	guard(mutex)(&cdev->ep1_out_mutex);
+
 	if (buffer && len > 0)
 		memcpy(cdev->ep1_out_buf+1, buffer, len);
 
@@ -235,6 +237,8 @@ int snd_usb_caiaq_send_command_bank(struct snd_usb_caiaqdev *cdev,
 	if (len > EP1_BUFSIZE - 2)
 		len = EP1_BUFSIZE - 2;
 
+	guard(mutex)(&cdev->ep1_out_mutex);
+
 	if (buffer && len > 0)
 		memcpy(cdev->ep1_out_buf+2, buffer, len);
 
@@ -443,6 +447,7 @@ static int create_card(struct usb_device *usb_dev,
 	cdev->chip.usb_id = USB_ID(le16_to_cpu(usb_dev->descriptor.idVendor),
 				  le16_to_cpu(usb_dev->descriptor.idProduct));
 	spin_lock_init(&cdev->spinlock);
+	mutex_init(&cdev->ep1_out_mutex);
 
 	*cardp = card;
 	return 0;
diff --git a/sound/usb/caiaq/device.h b/sound/usb/caiaq/device.h
index 1c6f34693fa8..822d872c8ad1 100644
--- a/sound/usb/caiaq/device.h
+++ b/sound/usb/caiaq/device.h
@@ -2,6 +2,8 @@
 #ifndef CAIAQ_DEVICE_H
 #define CAIAQ_DEVICE_H
 
+#include <linux/mutex.h>
+
 #include "../usbaudio.h"
 
 #define USB_VID_NATIVEINSTRUMENTS 0x17cc
@@ -68,6 +70,7 @@ struct snd_usb_caiaqdev {
 
 	unsigned char ep1_in_buf[EP1_BUFSIZE];
 	unsigned char ep1_out_buf[EP1_BUFSIZE];
+	struct mutex ep1_out_mutex;	/* protects ep1_out_buf */
 	unsigned char midi_out_buf[EP1_BUFSIZE];
 
 	struct caiaq_device_spec spec;