diff --git a/flake.nix b/flake.nix
index f67a74f..5f368bc 100644
--- a/flake.nix
+++ b/flake.nix
@@ -36,7 +36,7 @@
       lib = pkgs.lib;
       pkgs-unstable = nixpkgs-unstable.legacyPackages.${controllerArch};
       machines = (lib.modules.evalModules { modules = [ (import ./nixos/machines) ]; }).config.machines;
-      physicalMachines = lib.filterAttrs (n: v: v.kind == "physical") machines;
+      physicalMachines = lib.filterAttrs (n: v: v.isPhysical) machines;
       mkNixosSystems = systemDef:
         builtins.mapAttrs
           (name: machine:
diff --git a/nixos/default.nix b/nixos/default.nix
index b97f171..a9e34ab 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -6,8 +6,8 @@
     disko.nixosModules.disko
     agenix.nixosModules.default
   ]
-  ++ lib.lists.optional (machine.kind == "physical") ./physical.nix
-  ++ lib.lists.optional (machine.kind == "virtual") ./virtual;
+  ++ lib.lists.optional machine.isPhysical ./physical.nix
+  ++ lib.lists.optional machine.isVirtual ./virtual;
 
   config = {
     time.timeZone = "Europe/Amsterdam";
diff --git a/nixos/machines/default.nix b/nixos/machines/default.nix
index 3404f2b..cfd113a 100644
--- a/nixos/machines/default.nix
+++ b/nixos/machines/default.nix
@@ -1,8 +1,7 @@
 { lib, ... }:
 let
-  machineOpts = { ... }: {
+  machineOpts = { config, ... }: {
     options = {
-      # TODO: rename to kind?
       kind = lib.mkOption {
         type = lib.types.enum [ "physical" "virtual" ];
         description = ''
@@ -36,6 +35,18 @@ let
         type = lib.types.bool;
       };
 
+      # Derived value
+      isPhysical = lib.mkOption {
+        default = config.kind == "physical";
+        type = lib.types.bool;
+      };
+
+      # Derived value
+      isVirtual = lib.mkOption {
+        default = config.kind == "virtual";
+        type = lib.types.bool;
+      };
+
       nixosModule = lib.mkOption {
         default = { ... }: { };
         type = lib.types.anything;
diff --git a/nixos/modules/networking/default.nix b/nixos/modules/networking/default.nix
index d437895..0717415 100644
--- a/nixos/modules/networking/default.nix
+++ b/nixos/modules/networking/default.nix
@@ -48,7 +48,7 @@ in {
 
   config = {
     networking = {
-      domain = if machine.kind == "physical" then "hyp" else "dmz";
+      domain = if machine.isPhysical then "hyp" else "dmz";
       nftables.enable = true;
       useDHCP = false;
 
@@ -117,7 +117,7 @@ in {
             networkConfig.Bridge = cfg.dmz.bridgeName;
           };
         })
-        (lib.optionalAttrs (machine.kind == "virtual") {
+        (lib.optionalAttrs machine.isVirtual {
           "30-main-nic" = {
             matchConfig.Name = "en*";
 
diff --git a/nixos/physical.nix b/nixos/physical.nix
index 74de363..281dc6f 100644
--- a/nixos/physical.nix
+++ b/nixos/physical.nix
@@ -57,7 +57,7 @@
 
     microvm.vms =
       let
-        vmsForHypervisor = lib.filterAttrs (n: v: v.kind == "virtual" && v.hypervisorName == config.networking.hostName) machines;
+        vmsForHypervisor = lib.filterAttrs (n: v: v.isVirtual && v.hypervisorName == config.networking.hostName) machines;
       in
       builtins.mapAttrs
         (name: vm:
diff --git a/nixos/virtual/docker_swarm.nix b/nixos/virtual/docker_swarm.nix
index 0323e42..55f7309 100644
--- a/nixos/virtual/docker_swarm.nix
+++ b/nixos/virtual/docker_swarm.nix
@@ -12,7 +12,7 @@ in
   };
 
   config = lib.mkIf cfg.enable {
-    lab.vm.shares = lib.mkIf (machine.kind == "virtual") [{
+    lab.vm.shares = lib.mkIf machine.isVirtual [{
       name = "docker";
       mountPoint = "/var/lib/docker";
     }];