Image API produces incorrect images

I have a scheme code like

(define rpi-boot-partition

(partition

(size (* 128 (expt 2 20)))

(label "BOOT")

(file-system "vfat")

(flags '())

(initializer (gexp initialize-efi-partition))))

(define rpi-root-partition

(partition

(size 'guess)

(label "RASPIROOT")

(file-system "ext4")

(flags '(boot))

(initializer (gexp initialize-root-partition))))

(define raspberry-pi-image

(image

(format 'disk-image)

(partitions (list rpi-boot-partition rpi-root-partition))))

The output is like that:

$ fdisk -l /gnu/store/hnsfs5a161f5hvymg7ar541qrml62yvv-raspberry-pi-barebones-raw-image

Device Boot Start End Sectors Size Id Type

/gnu/store/hnsfs5a161f5hvymg7ar541qrml62yvv-raspberry-pi-barebones-raw-image1 1 262144 262144 128M 83 Linux

/gnu/store/hnsfs5a161f5hvymg7ar541qrml62yvv-raspberry-pi-barebones-raw-image2 262145 3583688 3321544 1.6G 83 Linux

No boot flag is set on the first partition. The file system seems to be incorrect (ext* instead of vfat)

merge 55405 55406

merge 55405 55406

thanks

(duplicate)