Proper disko module import

hosts/nixos/lapetus/default.nix

@@ -1,6 +1,9 @@
 { config, ... }:
 let
   device = "/dev/sda";
+  disko = import ./partitions.nix {
+    devices = [ device ];
+  };
 in
 {
   imports = [
@@ -9,6 +12,7 @@ in
     ../common/optional/slambda.nix
 
     ./hardware-configuration.nix
+    disko
   ];
 
   # Set the name of this machine!
@@ -31,10 +35,6 @@ in
   #   zfs rollback -r zroot@blank
   # '';
 
-  disko.devices = import ./partitions.nix {
-    devices = [ device ];
-  };
-
   # Boot
   boot.loader.grub = {
     inherit device;

hosts/nixos/lapetus/partitions.nix

@@ -39,6 +39,7 @@
     zpool = {
       zroot = {
         type = "zpool";
+        mountpoint = "/";
 
         postCreateHook = ''
           zfs snapshot zroot@blank