diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
index 3d041e1c14..44372b0e8a 100755
--- a/ports/stm32/mboot/Makefile
+++ b/ports/stm32/mboot/Makefile
@@ -71,7 +71,7 @@ CFLAGS += -DBOARD_$(BOARD)
 CFLAGS += -DAPPLICATION_ADDR=$(TEXT0_ADDR)
 CFLAGS += -DFFCONF_H=\"ports/stm32/mboot/ffconf.h\"
 CFLAGS += -DLFS1_NO_MALLOC -DLFS1_NO_DEBUG -DLFS1_NO_WARN -DLFS1_NO_ERROR -DLFS1_NO_ASSERT
-CFLAGS += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT
+CFLAGS += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT -DLFS2_READONLY
 CFLAGS += -DBUILDING_MBOOT=1
 CFLAGS += -DMICROPY_HW_STM32WB_FLASH_SYNCRONISATION=0
 CFLAGS += -DBOOTLOADER_DFU_USB_VID=$(BOOTLOADER_DFU_USB_VID) -DBOOTLOADER_DFU_USB_PID=$(BOOTLOADER_DFU_USB_PID)