diff --git a/emmc-image.nix b/emmc-image.nix
index a2f0745..34dd5cc 100644
--- a/emmc-image.nix
+++ b/emmc-image.nix
@@ -61,15 +61,15 @@
 
         # Copy the rootfs into the SD image
         eval $(partx $img -o START,SECTORS --nr 3 --pairs)
-        dd conv=notrunc if=./root-fs.img of=$img seek=$((START/64)) count=$((SECTORS/64)) bs=$((512*64))
+        dd conv=notrunc if=./root-fs.img of=$img seek=$((START*512)) oflag=seek_bytes bs=1M
 
         # Copy u-boot into the SD image
         eval $(partx $img -o START,SECTORS --nr 2 --pairs)
-        dd conv=notrunc if=${pkgs.ubootHelios64}/u-boot.itb of=$img seek=$((START/64)) count=$((SECTORS/64)) bs=$((512*64))
+        dd conv=notrunc if=${pkgs.ubootHelios64}/u-boot.itb of=$img seek=$START count=$SECTORS
 
         # Copy bootloader into the SD image
         eval $(partx $img -o START,SECTORS --nr 1 --pairs)
-        dd conv=notrunc if=${pkgs.ubootHelios64}/idbloader.img of=$img seek=$((START/64)) count=$((SECTORS/64)) bs=$((512*64))
+        dd conv=notrunc if=${pkgs.ubootHelios64}/idbloader.img of=$img seek=$START count=$SECTORS
 
         zstd -v --no-progress $img -o $out/sd-image/${config.sdImage.imageName}.zstd
       '';