白い熊, 白い熊 写道: > (background_image > '("/home/shiroikuma/0/pictures/grub/gnu-grub.jpg"))))) The ‘invalid field specifier’ is ‘background_image’, which isn't part of the (undocumented) grub-theme record. Try something roughly like (unfortunately untested): (grub-theme (inherit %default-theme) (images (list (grub-image (aspect-ratio 4/3) ; or 16/9, &c., to match… (file (local-file "/home/shiroikuma/0/pictures/grub/gnu-grub.jpg")))))) ‘local-file’ takes care of creating an immutable copy of gnu-grub.jpg in the store, where it can be seen and safely used by the sandboxed build environment. Kind regards, T G-R