diff --git a/espflash/src/image_format.rs b/espflash/src/image_format.rs
index 2af83ece..eea82fc0 100644
--- a/espflash/src/image_format.rs
+++ b/espflash/src/image_format.rs
@@ -135,11 +135,23 @@ impl<'a> IdfBootloaderFormat<'a> {
         };
 
         // fetch the generated header from the bootloader
-        let mut header: ImageHeader = *from_bytes(&bootloader[0..size_of::<ImageHeader>()]);
+        let mut calc_bootloader_size = 0;
+        let bootloader_header_size = size_of::<ImageHeader>();
+        calc_bootloader_size += bootloader_header_size;
+        let mut header: ImageHeader = *from_bytes(&bootloader[0..bootloader_header_size]);
         if header.magic != ESP_MAGIC {
             return Err(Error::InvalidBootloader);
         }
 
+        for _ in 0..header.segment_count {
+            let segment: SegmentHeader = *from_bytes(
+                &bootloader
+                    [calc_bootloader_size..calc_bootloader_size + size_of::<SegmentHeader>()],
+            );
+            println!("{:X?}", segment);
+            calc_bootloader_size += segment.length as usize + size_of::<SegmentHeader>();
+        }
+
         // update the header if a user has specified any custom arguments
         if let Some(mode) = flash_settings.mode {
             header.flash_mode = mode as u8;
@@ -157,11 +169,23 @@ impl<'a> IdfBootloaderFormat<'a> {
         );
 
         // re-calculate hash of the bootloader - needed since we modified the header
-        let bootloader_len = bootloader.len();
+        // the hash is at the end of the bootloader, but the bootloader bytes are padded.
+        // the real end of the bootloader is the end of the segments plus the 16-byte aligned 1-byte checksum.
+        let bootloader_sha_start =
+            calc_bootloader_size + (16 - ((calc_bootloader_size + 1) % 16)) + 1;
+        println!("{}", bootloader_sha_start);
         let mut hasher = Sha256::new();
-        hasher.update(&bootloader[..bootloader_len - 32]);
+        hasher.update(&bootloader[..bootloader_sha_start]);
         let hash = hasher.finalize();
-        bootloader.to_mut()[bootloader_len - 32..].copy_from_slice(&hash);
+        println!(
+            "before: {:X?}",
+            &bootloader[bootloader_sha_start..bootloader_sha_start + 32]
+        );
+        bootloader.to_mut()[bootloader_sha_start..bootloader_sha_start + 32].copy_from_slice(&hash);
+        println!(
+            "after:  {:X?}",
+            &bootloader[bootloader_sha_start..bootloader_sha_start + 32]
+        );
 
         // write the header of the app
         // use the same settings as the bootloader