diff --git a/lib/fudo/initrd-network.nix b/lib/fudo/initrd-network.nix
index 1ced6e2..0c36062 100644
--- a/lib/fudo/initrd-network.nix
+++ b/lib/fudo/initrd-network.nix
@@ -43,7 +43,7 @@ in {
       ];
       initrd = let
         host-key-pkg = host-keys.${config.instance.hostname};
-        host-privkey = toPath "${host-key-pkg}/ssh_host_ed25519_key";
+        host-privkey = builtins.toPath "${host-key-pkg}/ssh_host_ed25519_key";
       in {
         network = {
           enable = true;