2 files changed, 3 insertions, 6 deletions
diff --git a/stmhal/usbdev/class/cdc_msc_hid/inc/usbd_cdc_msc_hid.h b/stmhal/usbdev/class/cdc_msc_hid/inc/usbd_cdc_msc_hid.h
index 7eca900ee..48d260bc2 100644
--- a/stmhal/usbdev/class/cdc_msc_hid/inc/usbd_cdc_msc_hid.h
+++ b/stmhal/usbdev/class/cdc_msc_hid/inc/usbd_cdc_msc_hid.h
@@ -58,7 +58,7 @@ typedef struct _USBD_STORAGE {
   int8_t (* GetCapacity) (uint8_t lun, uint32_t *block_num, uint16_t *block_size);
   int8_t (* IsReady) (uint8_t lun);
   int8_t (* IsWriteProtected) (uint8_t lun);
-  int8_t (* StopUnit)(uint8_t lun);
+  int8_t (* StartStopUnit)(uint8_t lun, uint8_t started);
   int8_t (* PreventAllowMediumRemoval)(uint8_t lun, uint8_t param0);
   int8_t (* Read) (uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len);
   int8_t (* Write)(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len);
diff --git a/stmhal/usbdev/class/cdc_msc_hid/src/usbd_msc_scsi.c b/stmhal/usbdev/class/cdc_msc_hid/src/usbd_msc_scsi.c
index 894812c18..366f1f00e 100644
--- a/stmhal/usbdev/class/cdc_msc_hid/src/usbd_msc_scsi.c
+++ b/stmhal/usbdev/class/cdc_msc_hid/src/usbd_msc_scsi.c
@@ -450,13 +450,10 @@ static int8_t SCSI_StartStopUnit(USBD_HandleTypeDef  *pdev, uint8_t lun, uint8_t
   hmsc->bot_data_length = 0;
 
   // On Mac OS X, when the device is ejected a SCSI_START_STOP_UNIT command is sent.
-  // params[1]==0 means stop, param[1]==1 seems to be something else (happens after the
-  // device is plugged in and mounted for some time, probably a keep alive).
+  // Bit 0 of params[4] is the START bit.
   // If we get a stop, we must really stop the device so that the Mac does not
   // automatically remount it.
-  if (params[1] == 0) {
-      ((USBD_StorageTypeDef *)pdev->pUserData)->StopUnit(lun);
-  }
+  ((USBD_StorageTypeDef *)pdev->pUserData)->StartStopUnit(lun, params[4] & 1);
 
   return 0;
 }