diff --git a/src/class/msc/msc.h b/src/class/msc/msc.h
index ca5615055..59df6bed6 100644
--- a/src/class/msc/msc.h
+++ b/src/class/msc/msc.h
@@ -100,13 +100,13 @@ typedef enum
 /// Command Block Wrapper
 typedef struct ATTR_PACKED
 {
-  uint32_t signature   ; ///< Signature that helps identify this data packet as a CBW. The signature field shall contain the value 43425355h (little endian), indicating a CBW.
-  uint32_t tag         ; ///< Tag sent by the host. The device shall echo the contents of this field back to the host in the dCSWTagfield of the associated CSW. The dCSWTagpositively associates a CSW with the corresponding CBW.
-  uint32_t xfer_bytes  ; ///< The number of bytes of data that the host expects to transfer on the Bulk-In or Bulk-Out endpoint (as indicated by the Direction bit) during the execution of this command. If this field is zero, the device and the host shall transfer no data between the CBW and the associated CSW, and the device shall ignore the value of the Direction bit in bmCBWFlags.
-  uint8_t  dir         ; ///< Bit 7 of this field define transfer direction \n - 0 : Data-Out from host to the device. \n - 1 : Data-In from the device to the host.
-  uint8_t  lun         ; ///< The device Logical Unit Number (LUN) to which the command block is being sent. For devices that support multiple LUNs, the host shall place into this field the LUN to which this command block is addressed. Otherwise, the host shall set this field to zero.
-  uint8_t  cmd_len     ; ///< The valid length of the CBWCBin bytes. This defines the valid length of the command block. The only legal values are 1 through 16
-  uint8_t  command[16] ; ///< The command block to be executed by the device. The device shall interpret the first cmd_len bytes in this field as a command block
+  uint32_t signature;   ///< Signature that helps identify this data packet as a CBW. The signature field shall contain the value 43425355h (little endian), indicating a CBW.
+  uint32_t tag;         ///< Tag sent by the host. The device shall echo the contents of this field back to the host in the dCSWTagfield of the associated CSW. The dCSWTagpositively associates a CSW with the corresponding CBW.
+  uint32_t total_bytes; ///< The number of bytes of data that the host expects to transfer on the Bulk-In or Bulk-Out endpoint (as indicated by the Direction bit) during the execution of this command. If this field is zero, the device and the host shall transfer no data between the CBW and the associated CSW, and the device shall ignore the value of the Direction bit in bmCBWFlags.
+  uint8_t dir;          ///< Bit 7 of this field define transfer direction \n - 0 : Data-Out from host to the device. \n - 1 : Data-In from the device to the host.
+  uint8_t lun;          ///< The device Logical Unit Number (LUN) to which the command block is being sent. For devices that support multiple LUNs, the host shall place into this field the LUN to which this command block is addressed. Otherwise, the host shall set this field to zero.
+  uint8_t cmd_len;      ///< The valid length of the CBWCBin bytes. This defines the valid length of the command block. The only legal values are 1 through 16
+  uint8_t command[16];  ///< The command block to be executed by the device. The device shall interpret the first cmd_len bytes in this field as a command block
 }msc_cbw_t;
 
 TU_VERIFY_STATIC(sizeof(msc_cbw_t) == 31, "size is not correct");
diff --git a/src/class/msc/msc_device.c b/src/class/msc/msc_device.c
index 830ce85b7..4d2f9249c 100644
--- a/src/class/msc/msc_device.c
+++ b/src/class/msc/msc_device.c
@@ -74,7 +74,7 @@ typedef struct {
 
   // Bulk Only Transfer (BOT) Protocol
   uint8_t  stage;
-  uint32_t data_len;
+  uint32_t total_len;
   uint32_t xferred_len; // numbered of bytes transferred so far in the Data Stage
 
   // Sense Response Data
@@ -251,12 +251,11 @@ int32_t proc_builtin_scsi(msc_cbw_t const * p_cbw, uint8_t* buffer, uint32_t buf
 
     case SCSI_CMD_MODE_SENSE_6:
     {
-      scsi_mode_sense6_resp_t const mode_resp =
-      {
-          .data_len             = 3,
-          .medium_type          = 0,
-          .device_specific_para = 0,
-          .block_descriptor_len = 0  // no block descriptor are included
+      scsi_mode_sense6_resp_t const mode_resp = {
+        .data_len = 3,
+        .medium_type = 0,
+        .device_specific_para = 0,
+        .block_descriptor_len = 0    // no block descriptor are included
       };
 
       ret = sizeof(mode_resp);
@@ -313,8 +312,8 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
       p_csw->data_residue = 0;
 
       /*------------- Parse command and prepare DATA -------------*/
-      p_msc->stage       = MSC_STAGE_DATA;
-      p_msc->data_len    = p_cbw->xfer_bytes;
+      p_msc->stage = MSC_STAGE_DATA;
+      p_msc->total_len = p_cbw->total_bytes;
       p_msc->xferred_len = 0;
 
       if (SCSI_CMD_READ_10 == p_cbw->command[0])
@@ -331,12 +330,12 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
         // 1. Zero : Invoke app callback, skip DATA and move to STATUS stage
         // 2. OUT  : queue transfer (invoke app callback after done)
         // 3. IN   : invoke app callback to get response
-        if ( p_cbw->xfer_bytes == 0)
+        if ( p_cbw->total_bytes == 0)
         {
           int32_t const cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, NULL, 0);
 
-          p_msc->data_len = 0;
-          p_msc->stage    = MSC_STAGE_STATUS;
+          p_msc->total_len = 0;
+          p_msc->stage = MSC_STAGE_STATUS;
 
           if ( cb_result < 0 )
           {
@@ -351,7 +350,7 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
         else if ( !BIT_TEST_(p_cbw->dir, 7) )
         {
           // OUT transfer
-          TU_ASSERT( dcd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, p_msc->data_len), TUSB_ERROR_DCD_EDPT_XFER );
+          TU_ASSERT( dcd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, p_msc->total_len), TUSB_ERROR_DCD_EDPT_XFER );
         }
         else
         {
@@ -364,21 +363,21 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
           // Not an built-in command, invoke user callback
           if ( cb_result < 0 )
           {
-            cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->data_len);
+            cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->total_len);
           }
 
           if ( cb_result > 0 )
           {
-            p_msc->data_len = (uint32_t) cb_result;
-            p_csw->status   = MSC_CSW_STATUS_PASSED;
+            p_msc->total_len = (uint32_t) cb_result;
+            p_csw->status = MSC_CSW_STATUS_PASSED;
 
-            TU_ASSERT( p_cbw->xfer_bytes >= p_msc->data_len, TUSB_ERROR_INVALID_PARA ); // cannot return more than host expect
-            TU_ASSERT( dcd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, p_msc->data_len), TUSB_ERROR_DCD_EDPT_XFER );
+            TU_ASSERT( p_cbw->total_bytes >= p_msc->total_len, TUSB_ERROR_INVALID_PARA ); // cannot return more than host expect
+            TU_ASSERT( dcd_edpt_xfer(rhport, p_msc->ep_in, _mscd_buf, p_msc->total_len), TUSB_ERROR_DCD_EDPT_XFER );
           }else
           {
-            p_msc->data_len = 0;
-            p_csw->status   = MSC_CSW_STATUS_FAILED;
-            p_msc->stage    = MSC_STAGE_STATUS;
+            p_msc->total_len = 0;
+            p_csw->status = MSC_CSW_STATUS_FAILED;
+            p_msc->stage = MSC_STAGE_STATUS;
 
             tud_msc_set_sense(p_cbw->lun, SCSI_SENSE_ILLEGAL_REQUEST, 0x20, 0x00); // Sense = Invalid Command Operation
             dcd_edpt_stall(rhport, p_msc->ep_in);
@@ -393,7 +392,7 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
       {
         if ( SCSI_CMD_WRITE_10 != p_cbw->command[0] )
         {
-          int32_t cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->data_len);
+          int32_t cb_result = tud_msc_scsi_cb(p_cbw->lun, p_cbw->command, _mscd_buf, p_msc->total_len);
 
           if ( cb_result < 0 )
           {
@@ -406,7 +405,7 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
         }
         else
         {
-          uint16_t const block_sz = p_cbw->xfer_bytes / rdwr10_get_blockcount(p_cbw->command);
+          uint16_t const block_sz = p_cbw->total_bytes / rdwr10_get_blockcount(p_cbw->command);
 
           // Adjust lba with transferred bytes
           uint32_t const lba = rdwr10_get_lba(p_cbw->command) + (p_msc->xferred_len / block_sz);
@@ -417,7 +416,7 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
           if ( nbytes < 0 )
           {
             // negative means error -> skip to status phase, status in CSW set to failed
-            p_csw->data_residue = p_cbw->xfer_bytes - p_msc->xferred_len;
+            p_csw->data_residue = p_cbw->total_bytes - p_msc->xferred_len;
             p_csw->status       = MSC_CSW_STATUS_FAILED;
             p_msc->stage        = MSC_STAGE_STATUS;
 
@@ -450,7 +449,7 @@ tusb_error_t mscd_xfer_cb(uint8_t rhport, uint8_t ep_addr, tusb_event_t event, u
       // Accumulate data so far
       p_msc->xferred_len += xferred_bytes;
 
-      if ( p_msc->xferred_len >= p_msc->data_len )
+      if ( p_msc->xferred_len >= p_msc->total_len )
       {
         // Data Stage is complete
         p_msc->stage = MSC_STAGE_STATUS;
@@ -523,13 +522,13 @@ static void proc_read10_cmd(uint8_t rhport, mscd_interface_t* p_msc)
   msc_cbw_t const * p_cbw = &p_msc->cbw;
   msc_csw_t       * p_csw = &p_msc->csw;
 
-  uint16_t const block_sz = p_cbw->xfer_bytes / rdwr10_get_blockcount(p_cbw->command);
+  uint16_t const block_sz = p_cbw->total_bytes / rdwr10_get_blockcount(p_cbw->command);
 
   // Adjust lba with transferred bytes
   uint32_t const lba = rdwr10_get_lba(p_cbw->command) + (p_msc->xferred_len / block_sz);
 
   // remaining bytes capped at class buffer
-  int32_t nbytes = (int32_t) tu_min32(sizeof(_mscd_buf), p_cbw->xfer_bytes-p_msc->xferred_len);
+  int32_t nbytes = (int32_t) tu_min32(sizeof(_mscd_buf), p_cbw->total_bytes-p_msc->xferred_len);
 
   // Application can consume smaller bytes
   nbytes = tud_msc_read10_cb(p_cbw->lun, lba, p_msc->xferred_len % block_sz, _mscd_buf, (uint32_t) nbytes);
@@ -537,7 +536,7 @@ static void proc_read10_cmd(uint8_t rhport, mscd_interface_t* p_msc)
   if ( nbytes < 0 )
   {
     // negative means error -> pipe is stalled & status in CSW set to failed
-    p_csw->data_residue = p_cbw->xfer_bytes - p_msc->xferred_len;
+    p_csw->data_residue = p_cbw->total_bytes - p_msc->xferred_len;
     p_csw->status       = MSC_CSW_STATUS_FAILED;
 
     tud_msc_set_sense(p_cbw->lun, SCSI_SENSE_ILLEGAL_REQUEST, 0x20, 0x00); // Sense = Invalid Command Operation
@@ -559,7 +558,7 @@ static void proc_write10_cmd(uint8_t rhport, mscd_interface_t* p_msc)
   msc_cbw_t const * p_cbw = &p_msc->cbw;
 
   // remaining bytes capped at class buffer
-  int32_t nbytes = (int32_t) tu_min32(sizeof(_mscd_buf), p_cbw->xfer_bytes-p_msc->xferred_len);
+  int32_t nbytes = (int32_t) tu_min32(sizeof(_mscd_buf), p_cbw->total_bytes-p_msc->xferred_len);
 
   // Write10 callback will be called later when usb transfer complete
   TU_ASSERT( dcd_edpt_xfer(rhport, p_msc->ep_out, _mscd_buf, nbytes), );