diff --git a/ports/stm32/sdcard.c b/ports/stm32/sdcard.c
index 7d79e9f47b..b255ee82ca 100644
--- a/ports/stm32/sdcard.c
+++ b/ports/stm32/sdcard.c
@@ -866,7 +866,9 @@ void sdcard_init_vfs(fs_user_mount_t *vfs, int part) {
     vfs->base.type = &mp_fat_vfs_type;
     vfs->blockdev.flags |= MP_BLOCKDEV_FLAG_NATIVE | MP_BLOCKDEV_FLAG_HAVE_IOCTL;
     vfs->fatfs.drv = vfs;
+    #if MICROPY_FATFS_MULTI_PARTITION
     vfs->fatfs.part = part;
+    #endif
     vfs->blockdev.readblocks[0] = MP_OBJ_FROM_PTR(&pyb_sdcard_readblocks_obj);
     vfs->blockdev.readblocks[1] = MP_OBJ_FROM_PTR(&pyb_sdcard_obj);
     vfs->blockdev.readblocks[2] = MP_OBJ_FROM_PTR(sdcard_read_blocks); // native version
diff --git a/ports/stm32/storage.c b/ports/stm32/storage.c
index 0fefcbab90..c8805d6829 100644
--- a/ports/stm32/storage.c
+++ b/ports/stm32/storage.c
@@ -453,7 +453,9 @@ void pyb_flash_init_vfs(fs_user_mount_t *vfs) {
     vfs->base.type = &mp_fat_vfs_type;
     vfs->blockdev.flags |= MP_BLOCKDEV_FLAG_NATIVE | MP_BLOCKDEV_FLAG_HAVE_IOCTL;
     vfs->fatfs.drv = vfs;
+    #if MICROPY_FATFS_MULTI_PARTITION
     vfs->fatfs.part = 1; // flash filesystem lives on first partition
+    #endif
     vfs->blockdev.readblocks[0] = MP_OBJ_FROM_PTR(&pyb_flash_readblocks_obj);
     vfs->blockdev.readblocks[1] = MP_OBJ_FROM_PTR(&pyb_flash_obj);
     vfs->blockdev.readblocks[2] = MP_OBJ_FROM_PTR(storage_read_blocks); // native version