diff --git a/src/usb/msc_uf2.h b/src/usb/msc_uf2.h
index c325d21..fdbbe55 100644
--- a/src/usb/msc_uf2.h
+++ b/src/usb/msc_uf2.h
@@ -44,21 +44,22 @@
 
 // for checking flash size
 #include "dfu_types.h"
+#include "uf2/uf2.h"
 
 /*------------------------------------------------------------------*/
 /* FLASH Configuration
  *------------------------------------------------------------------*/
-#define MSC_FLASH_ADDR_START      0xAD000
-#define MSC_FLASH_SIZE            (256*1024)
+#define MSC_FLASH_ADDR_START    0xAD000
+#define MSC_FLASH_SIZE          (256*1024)
 
-#define MSC_FLASH_BLOCK_SIZE      512
-#define MSC_FLASH_BLOCK_NUM       (MSC_FLASH_SIZE/MSC_FLASH_BLOCK_SIZE)
-
-VERIFY_STATIC( MSC_FLASH_ADDR_START+MSC_FLASH_SIZE == BOOTLOADER_REGION_START-DFU_APP_DATA_RESERVED, );
+#define MSC_UF2_BLOCK_SIZE      512
+#define MSC_UF2_BLOCK_NUM       UF2_NUM_BLOCKS
 
 // must be 11 bytes padded with space
 #define MSC_FLASH_VOL_LABEL       "NRF52BOOT  "
 
+VERIFY_STATIC( MSC_FLASH_ADDR_START+MSC_FLASH_SIZE == BOOTLOADER_REGION_START-DFU_APP_DATA_RESERVED, );
+
 /*------------------------------------------------------------------*/
 /* Note ATTR_WEAK is used when CFG_TUD_MSC = 0
  *------------------------------------------------------------------*/