Index: uspace/drv/bus/usb/usbmast/bo_trans.c
===================================================================
--- uspace/drv/bus/usb/usbmast/bo_trans.c	(revision 7190bbc89aaedaf0490a4a0b475282502e125bfc)
+++ uspace/drv/bus/usb/usbmast/bo_trans.c	(revision e6b32a8bd052699b36d163edb8ab9a99071ac6fc)
@@ -58,5 +58,4 @@
  * @param tag		Command block wrapper tag (automatically compared
  *			with answer)
- * @param lun		LUN
  * @param cmd		Command block
  * @param cmd_size	Command block size in bytes
@@ -68,7 +67,7 @@
  * @return		Error code
  */
-static int usb_massstor_cmd(usbmast_fun_t *mfun, uint32_t tag, uint8_t lun,
-    const void *cmd, size_t cmd_size, usb_direction_t ddir, void *dbuf,
-    size_t dbuf_size, size_t *xferred_size)
+static int usb_massstor_cmd(usbmast_fun_t *mfun, uint32_t tag, const void *cmd,
+    size_t cmd_size, usb_direction_t ddir, void *dbuf, size_t dbuf_size,
+    size_t *xferred_size)
 {
 	int rc;
@@ -79,6 +78,6 @@
 	/* Prepare CBW - command block wrapper */
 	usb_massstor_cbw_t cbw;
-	usb_massstor_cbw_prepare(&cbw, tag, dbuf_size, ddir, lun, cmd_size,
-	    cmd);
+	usb_massstor_cbw_prepare(&cbw, tag, dbuf_size, ddir, mfun->lun,
+	    cmd_size, cmd);
 
 	/* Send the CBW. */
@@ -170,5 +169,4 @@
  * @param tag		Command block wrapper tag (automatically compared with
  *			answer)
- * @param lun		LUN
  * @param cmd		CDB (Command Descriptor)
  * @param cmd_size	CDB length in bytes
@@ -179,8 +177,8 @@
  * @return Error code
  */
-int usb_massstor_data_in(usbmast_fun_t *mfun, uint32_t tag, uint8_t lun,
-    const void *cmd, size_t cmd_size, void *dbuf, size_t dbuf_size, size_t *proc_size)
-{
-	return usb_massstor_cmd(mfun, tag, lun, cmd, cmd_size, USB_DIRECTION_IN,
+int usb_massstor_data_in(usbmast_fun_t *mfun, uint32_t tag, const void *cmd,
+    size_t cmd_size, void *dbuf, size_t dbuf_size, size_t *proc_size)
+{
+	return usb_massstor_cmd(mfun, tag, cmd, cmd_size, USB_DIRECTION_IN,
 	    dbuf, dbuf_size, proc_size);
 }
@@ -191,5 +189,4 @@
  * @param tag		Command block wrapper tag (automatically compared with
  *			answer)
- * @param lun		LUN
  * @param cmd		CDB (Command Descriptor)
  * @param cmd_size	CDB length in bytes
@@ -200,9 +197,8 @@
  * @return Error code
  */
-int usb_massstor_data_out(usbmast_fun_t *mfun, uint32_t tag, uint8_t lun,
-    const void *cmd, size_t cmd_size, const void *data, size_t data_size,
-    size_t *proc_size)
-{
-	return usb_massstor_cmd(mfun, tag, lun, cmd, cmd_size, USB_DIRECTION_OUT,
+int usb_massstor_data_out(usbmast_fun_t *mfun, uint32_t tag, const void *cmd,
+    size_t cmd_size, const void *data, size_t data_size, size_t *proc_size)
+{
+	return usb_massstor_cmd(mfun, tag, cmd, cmd_size, USB_DIRECTION_OUT,
 	    (void *) data, data_size, proc_size);
 }
Index: uspace/drv/bus/usb/usbmast/bo_trans.h
===================================================================
--- uspace/drv/bus/usb/usbmast/bo_trans.h	(revision 7190bbc89aaedaf0490a4a0b475282502e125bfc)
+++ uspace/drv/bus/usb/usbmast/bo_trans.h	(revision e6b32a8bd052699b36d163edb8ab9a99071ac6fc)
@@ -47,8 +47,8 @@
 #define BULK_OUT_EP 1
 
-extern int usb_massstor_data_in(usbmast_fun_t *, uint32_t, uint8_t,
-    const void *, size_t, void *, size_t, size_t *);
-extern int usb_massstor_data_out(usbmast_fun_t *, uint32_t, uint8_t,
-    const void *, size_t, const void *, size_t, size_t *);
+extern int usb_massstor_data_in(usbmast_fun_t *, uint32_t, const void *,
+    size_t, void *, size_t, size_t *);
+extern int usb_massstor_data_out(usbmast_fun_t *, uint32_t, const void *,
+    size_t, const void *, size_t, size_t *);
 extern int usb_massstor_reset(usbmast_fun_t *);
 extern void usb_massstor_reset_recovery(usbmast_fun_t *);
Index: uspace/drv/bus/usb/usbmast/main.c
===================================================================
--- uspace/drv/bus/usb/usbmast/main.c	(revision 7190bbc89aaedaf0490a4a0b475282502e125bfc)
+++ uspace/drv/bus/usb/usbmast/main.c	(revision e6b32a8bd052699b36d163edb8ab9a99071ac6fc)
@@ -102,4 +102,5 @@
 
 	msfun->usb_dev = dev;
+	msfun->lun = 0;
 
 	fun = ddf_fun_create(dev->ddf_dev, fun_exposed, fun_name);
Index: uspace/drv/bus/usb/usbmast/scsi_ms.c
===================================================================
--- uspace/drv/bus/usb/usbmast/scsi_ms.c	(revision 7190bbc89aaedaf0490a4a0b475282502e125bfc)
+++ uspace/drv/bus/usb/usbmast/scsi_ms.c	(revision e6b32a8bd052699b36d163edb8ab9a99071ac6fc)
@@ -78,5 +78,5 @@
 	cdb.alloc_len = host2uint16_t_be(sizeof(inq_data));
 
-	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, 0, (uint8_t *) &cdb,
+	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, (uint8_t *) &cdb,
 	    sizeof(cdb), &inq_data, sizeof(inq_data), &response_len);
 
@@ -135,5 +135,5 @@
 	cdb.alloc_len = min(size, SCSI_SENSE_DATA_MAX_SIZE);
 
-	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, 0, (uint8_t *) &cdb,
+	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, (uint8_t *) &cdb,
 	    sizeof(cdb), buf, size, &data_len);
 
@@ -172,5 +172,5 @@
 	cdb.op_code = SCSI_CMD_READ_CAPACITY_10;
 
-	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, 0, (uint8_t *) &cdb,
+	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, (uint8_t *) &cdb,
 	    sizeof(cdb), &data, sizeof(data), &data_len);
 
@@ -220,5 +220,5 @@
 	cdb.xfer_len = host2uint32_t_be(nblocks);
 
-	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, 0, (uint8_t *) &cdb,
+	rc = usb_massstor_data_in(mfun, 0xDEADBEEF, (uint8_t *) &cdb,
 	    sizeof(cdb), buf, nblocks * mfun->block_size, &data_len);
 
@@ -265,5 +265,5 @@
 	cdb.xfer_len = host2uint32_t_be(nblocks);
 
-	rc = usb_massstor_data_out(mfun, 0xDEADBEEF, 0, (uint8_t *) &cdb,
+	rc = usb_massstor_data_out(mfun, 0xDEADBEEF, (uint8_t *) &cdb,
 	    sizeof(cdb), data, nblocks * mfun->block_size, &sent_len);
 
Index: uspace/drv/bus/usb/usbmast/usbmast.h
===================================================================
--- uspace/drv/bus/usb/usbmast/usbmast.h	(revision 7190bbc89aaedaf0490a4a0b475282502e125bfc)
+++ uspace/drv/bus/usb/usbmast/usbmast.h	(revision e6b32a8bd052699b36d163edb8ab9a99071ac6fc)
@@ -47,4 +47,6 @@
 	/** DDF function */
 	ddf_fun_t *ddf_fun;
+	/** LUN */
+	unsigned lun;
 	/** Total number of blocks. */
 	uint64_t nblocks;