diff --git a/pkgs/by-name/bootpart-edk2-rpi/package.nix b/pkgs/by-name/bootpart-edk2-rpi/package.nix
index 8104e6dec..1805a1d9a 100644
--- a/pkgs/by-name/bootpart-edk2-rpi/package.nix
+++ b/pkgs/by-name/bootpart-edk2-rpi/package.nix
@@ -20,9 +20,11 @@ runCommandLocal "bootpart-edk2-rpi" {
   install -Dm644 ${./config.txt} $out/config.txt
   install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/fixup4.dat $out/fixup4.dat
   install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/start4.elf $out/start4.elf
-  # XXX: .dtb files don't seem to be required for the edk2 firmware to load.
-  # i'm not sure what i lose by omitting them.
-  # install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/bcm2711-rpi-400.dtb $out/bcm2711-rpi-400.dtb
+  # N.B.: there are weird incompatibilities between raspberrypifw (start4.elf) and edk2.
+  # it seems that if the two binaries are on different versions, then the dtb resolves some discrepencies:
+  # - allows systemd-boot to autoboot after 5s (else, it lacks its countdown ... uart problems?)
+  # but generally, omitting this .dtb probably won't totally break the boot.
+  install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/bcm2711-rpi-400.dtb $out/bcm2711-rpi-400.dtb
   # install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/bcm2711-rpi-4-b.dtb $out/bcm2711-rpi-4-b.dtb
   # install -Dm644 ${raspberrypifw}/share/raspberrypi/boot/bcm2711-rpi-cm4.dtb $out/bcm2711-rpi-cm4.dtb
 ''