diff --git a/demos/device/device_os_none/mscd_app.c b/demos/device/device_os_none/mscd_app.c
index dc934e4ae..bbb4df587 100644
--- a/demos/device/device_os_none/mscd_app.c
+++ b/demos/device/device_os_none/mscd_app.c
@@ -65,7 +65,7 @@ static scsi_read_capacity10_data_t mscd_read_capacity10_data TUSB_CFG_ATTR_USBRA
 };
 
 ATTR_USB_MIN_ALIGNMENT
-static scsi_sense_fixed_data_t mscd_sense_data TUSB_CFG_ATTR_USBRAM =
+scsi_sense_fixed_data_t mscd_sense_data TUSB_CFG_ATTR_USBRAM =
 {
     .response_code        = 0x70,
     .sense_key            = 0, // no errors
@@ -140,6 +140,14 @@ msc_csw_status_t tusbd_msc_scsi_received_isr (uint8_t coreid, uint8_t lun, uint8
     default: return MSC_CSW_STATUS_FAILED;
   }
 
+  //------------- clear sense data if it is not request sense command -------------//
+  if ( SCSI_CMD_REQUEST_SENSE != scsi_cmd[0] )
+  {
+    mscd_sense_data.sense_key                  = SCSI_SENSEKEY_NONE;
+    mscd_sense_data.additional_sense_code      = 0;
+    mscd_sense_data.additional_sense_qualifier = 0;
+  }
+
   return MSC_CSW_STATUS_PASSED;
 }
 
diff --git a/demos/device/device_os_none/mscd_app.h b/demos/device/device_os_none/mscd_app.h
index cf57db75a..f9f1d20bc 100644
--- a/demos/device/device_os_none/mscd_app.h
+++ b/demos/device/device_os_none/mscd_app.h
@@ -75,6 +75,8 @@ issue at github.com/hathach/tinyusb"
 void msc_dev_app_init(void);
 OSAL_TASK_FUNCTION( msc_dev_app_task ) (void* p_task_para);
 
+extern scsi_sense_fixed_data_t mscd_sense_data;
+
 #else
 
 #define msc_dev_app_init()
diff --git a/demos/device/device_os_none/mscd_app_romdisk.c b/demos/device/device_os_none/mscd_app_romdisk.c
index 9f7723b6a..4cb4d5368 100644
--- a/demos/device/device_os_none/mscd_app_romdisk.c
+++ b/demos/device/device_os_none/mscd_app_romdisk.c
@@ -103,6 +103,9 @@ uint16_t tusbd_msc_read10_cb (uint8_t coreid, uint8_t lun, void** pp_buffer, uin
 uint16_t tusbd_msc_write10_cb(uint8_t coreid, uint8_t lun, void** pp_buffer, uint32_t lba, uint16_t block_count)
 {
   (*pp_buffer) = NULL;
+
+  mscd_sense_data.sense_key = SCSI_SENSEKEY_DATA_PROTECT; // let host know that this is read-only disk
+
   return 0;
 }
 
diff --git a/tinyusb/class/msc.h b/tinyusb/class/msc.h
index d80e368e3..2c6adb2d6 100644
--- a/tinyusb/class/msc.h
+++ b/tinyusb/class/msc.h
@@ -55,9 +55,8 @@
 #endif
 
 //--------------------------------------------------------------------+
-// USB Class Constant
+// Mass Storage Class Constant
 //--------------------------------------------------------------------+
-
 /// MassStorage Subclass
 typedef enum {
   MSC_SUBCLASS_RBC = 1 , ///< Reduced Block Commands (RBC) T10 Project 1240-D
@@ -119,6 +118,10 @@ typedef ATTR_PACKED_STRUCT(struct) {
 
 STATIC_ASSERT(sizeof(msc_cmd_status_wrapper_t) == 13, "size is not correct");
 
+//--------------------------------------------------------------------+
+// SCSI Constant
+//--------------------------------------------------------------------+
+
 /// SCSI Command Operation Code
 typedef enum {
   SCSI_CMD_TEST_UNIT_READY              = 0x00, ///< The SCSI Test Unit Ready command is used to determine if a device is ready to transfer data (read/write), i.e. if a disk has spun up, if a tape is loaded and ready etc. The device does not perform a self-test operation.
@@ -133,6 +136,23 @@ typedef enum {
   SCSI_CMD_WRITE_10                     = 0x2A, ///< The WRITE (10) command requests thatthe device server transfer the specified logical block(s) from the data-out buffer and write them.
 }scsi_cmd_type_t;
 
+/// SCSI Sense Key
+typedef enum {
+  SCSI_SENSEKEY_NONE            = 0x00, ///< no specific Sense Key. This would be the case for a successful command
+  SCSI_SENSEKEY_RECOVERED_ERROR = 0x01, ///< ndicates the last command completed successfully with some recovery action performed by the disc drive.
+  SCSI_SENSEKEY_NOT_READY       = 0x02, ///< Indicates the logical unit addressed cannot be accessed.
+  SCSI_SENSEKEY_MEDIUM_ERROR    = 0x03, ///< Indicates the command terminated with a non-recovered error condition.
+  SCSI_SENSEKEY_HARDWARE_ERROR  = 0x04, ///< Indicates the disc drive detected a nonrecoverable hardware failure while performing the command or during a self test.
+  SCSI_SENSEKEY_ILLEGLA_REQUEST = 0x05, ///< Indicates an illegal parameter in the command descriptor block or in the additional parameters
+  SCSI_SENSEKEY_UNIT_ATTENTION  = 0x06, ///< Indicates the disc drive may have been reset.
+  SCSI_SENSEKEY_DATA_PROTECT    = 0x07, ///< Indicates that a command that reads or writes the medium was attempted on a block that is protected from this operation. The read or write operation is not performed.
+  SCSI_SENSEKEY_FIRMWARE_ERROR  = 0x08, ///< Vendor specific sense key.
+  SCSI_SENSEKEY_ABORTED_COMMAND = 0x0b, ///< Indicates the disc drive aborted the command.
+  SCSI_SENSEKEY_EQUAL           = 0x0c, ///< Indicates a SEARCH DATA command has satisfied an equal comparison.
+  SCSI_SENSEKEY_VOLUME_OVERFLOW = 0x0d, ///< Indicates a buffered peripheral device has reached the end of medium partition and data remains in the buffer that has not been written to the medium.
+  SCSI_SENSEKEY_MISCOMPARE      = 0x0e  ///< ndicates that the source data did not match the data read from the medium.
+}scsi_sense_key_type_t;
+
 //--------------------------------------------------------------------+
 // SCSI Primary Command (SPC-4)
 //--------------------------------------------------------------------+