diff --git a/host-registry.nix b/host-registry.nix
index 83312477..38b2fe2b 100644
--- a/host-registry.nix
+++ b/host-registry.nix
@@ -22,6 +22,7 @@ rec {
         "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIE9RKlt+mIew5epxHt7Gab44yFOdeD+L/EhhA6Ospzyq";
       builders = [ "ssh://client@172.22.99.110" ];
       wol = true;
+      raspberryPi = 3;
     };
     samba = { };
     storage-ng.publicKey =
@@ -119,6 +120,7 @@ rec {
     };
 
     radiobert.ip4 = "172.22.99.117";
+    radiobert.rasbperryPi = 4;
   };
 
   hqGlobal = builtins.attrNames hosts;
diff --git a/lib/default.nix b/lib/default.nix
index f637ecb6..d083f3d1 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -2,7 +2,7 @@
 # That includes physical servers, VMs, containers, and personal machines.
 #
 
-{ inputs, config, lib, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 
 let
   hqPrefix64 = "fd23:42:c3d2:523";
@@ -31,8 +31,8 @@ in {
     ./users
     ./stats.nix
     ./openwebrx.nix
-  ]
-  ++ lib.optional config.boot.loader.raspberryPi.enable "${inputs.nixpkgs}/nixos/modules/installer/sd-card/sd-image-aarch64.nix";
+    ./raspberrypi.nix
+  ];
 
   options.c3d2 = with lib;
     with lib.types; {
diff --git a/lib/raspberrypi.nix b/lib/raspberrypi.nix
new file mode 100644
index 00000000..16d53269
--- /dev/null
+++ b/lib/raspberrypi.nix
@@ -0,0 +1,21 @@
+{ inputs, hostRegistry, options, lib, ... }:
+
+let
+  enabled = hostRegistry.hosts.${config.networking.hostName} ? raspberryPi &&
+            hostRegistry.hosts.${config.networking.hostName}.raspberryPi != null;
+in
+{
+  imports = lib.optionals enabled [
+    "${inputs.nixpkgs}/nixos/modules/installer/sd-card/sd-image-aarch64.nix"
+  ];
+  config = lib.mkIf enabled {
+    sdImage = {
+      compressImage = false;
+      imageBaseName = config.networking.hostName;
+      firmwareSize = 512;
+    };
+    # Don't build ZFS for aarch64 (broken?)
+    boot.supportedFilesystems = lib.mkForce [ "vfat" "ext4" ];
+    boot.zfs.enableUnstable = true;
+  };
+}