diff --git a/src/storage/spiflash.rs b/src/storage/spiflash.rs
index f3165f6..47ba956 100644
--- a/src/storage/spiflash.rs
+++ b/src/storage/spiflash.rs
@@ -50,6 +50,9 @@ impl SPIFlashStorage {
         let mut drive: u8 = 0;
         esp!(unsafe { ff_diskio_get_drive(&mut drive) })?;
         let fatfs = unsafe { Fatfs::new_wl_part(drive, self.handle()) }?;
+        // TODO: handle file system not formatted issue.
+        //       looks like esp-idf-svc didn't implement error handling at this moment:
+        //       https://github.com/esp-rs/esp-idf-svc/blob/6453bedd5967ebc3bcb7d240492a0d5164e818c2/src/io.rs#L130
         self.mounted_fatfs = Some(MountedFatfs::mount(fatfs, mount_path, max_fds)?);
         Ok(())
     }