diff --git a/.forgejo/workflows/build.yaml b/.forgejo/workflows/build.yaml
index ee97846..89693ab 100644
--- a/.forgejo/workflows/build.yaml
+++ b/.forgejo/workflows/build.yaml
@@ -8,4 +8,4 @@ jobs:
     runs-on: native
     steps:
       - uses: actions/checkout@v4
-      - run: nix-build -A ci.check
+      - run: nix flake check --all-systems
diff --git a/default.nix b/default.nix
deleted file mode 100644
index bb13b3b..0000000
--- a/default.nix
+++ /dev/null
@@ -1,8 +0,0 @@
-let
-  nilla = import ./nilla.nix { };
-  getPackage = name: nilla.packages.${name}.result.${builtins.currentSystem};
-in
-{
-  ci.check = getPackage "ci-check";
-  formatter = getPackage "formatter";
-}
diff --git a/hosts/default.nix b/hosts/default.nix
index 843a8d1..3c8b713 100644
--- a/hosts/default.nix
+++ b/hosts/default.nix
@@ -16,7 +16,7 @@ in
     ./youko
   ];
 
-  config.systems.builders =
+  config.configBuilders =
     let
       sharedOptions = {
         _file = ./default.nix;
diff --git a/hosts/hijiri-vm/default.nix b/hosts/hijiri-vm/default.nix
index 94350be..5f6d088 100644
--- a/hosts/hijiri-vm/default.nix
+++ b/hosts/hijiri-vm/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.nixos.hijiri-vm.module =
+  config.configurations.nixos.hijiri-vm =
     {
       modulesPath,
       lib,
diff --git a/hosts/hijiri/default.nix b/hosts/hijiri/default.nix
index 66defb4..a0e6857 100644
--- a/hosts/hijiri/default.nix
+++ b/hosts/hijiri/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.darwin.hijiri.module =
+  config.configurations.darwin.hijiri =
     {
       config,
       pkgs,
diff --git a/hosts/kazuki/default.nix b/hosts/kazuki/default.nix
index d0fad10..029d7d0 100644
--- a/hosts/kazuki/default.nix
+++ b/hosts/kazuki/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.nixos.kazuki.module =
+  config.configurations.nixos.kazuki =
     {
       modulesPath,
       ...
diff --git a/hosts/kogata/default.nix b/hosts/kogata/default.nix
index d5ac7cb..3e7c21f 100644
--- a/hosts/kogata/default.nix
+++ b/hosts/kogata/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.darwin.kogata.module =
+  config.configurations.darwin.kogata =
     { pkgs, ... }:
     {
       nixpkgs.system = "aarch64-darwin";
diff --git a/hosts/ude/default.nix b/hosts/ude/default.nix
index 62ffb2e..fd3e19b 100644
--- a/hosts/ude/default.nix
+++ b/hosts/ude/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.nixos.ude.module =
+  config.configurations.nixos.ude =
     {
       config,
       modulesPath,
diff --git a/hosts/youko/default.nix b/hosts/youko/default.nix
index 7f39ac5..b801507 100644
--- a/hosts/youko/default.nix
+++ b/hosts/youko/default.nix
@@ -1,5 +1,5 @@
 {
-  config.systems.nixos.youko.module =
+  config.configurations.nixos.youko =
     {
       config,
       lib,
diff --git a/modules/nilla/configurations.nix b/modules/nilla/configurations.nix
new file mode 100644
index 0000000..6f02f7e
--- /dev/null
+++ b/modules/nilla/configurations.nix
@@ -0,0 +1,47 @@
+{ config, lib }:
+{
+  options = {
+    configBuilders = {
+      nixos = lib.options.create {
+        type = lib.types.function lib.types.raw;
+        default.value = _name: config.inputs.nixpkgs.result.lib.nixosSystem;
+      };
+      darwin = lib.options.create {
+        type = lib.types.function lib.types.raw;
+        default.value = _name: config.inputs.darwin.result.lib.darwinSystem;
+      };
+      home = lib.options.create {
+        type = lib.types.function lib.types.raw;
+        default.value = _name: config.inputs.home-manager.result.lib.homeManagerConfiguration;
+      };
+    };
+
+    configurations = {
+      nixos = lib.options.create {
+        type = lib.types.attrs.lazy lib.types.raw;
+        default.value = { };
+      };
+      darwin = lib.options.create {
+        type = lib.types.attrs.lazy lib.types.raw;
+        default.value = { };
+      };
+      home = lib.options.create {
+        type = lib.types.attrs.lazy lib.types.raw;
+        default.value = { };
+      };
+    };
+
+    nixosConfigurations = lib.options.create {
+      type = lib.types.attrs.lazy lib.types.raw;
+      default.value = builtins.mapAttrs config.configBuilders.nixos config.configurations.nixos;
+    };
+    darwinConfigurations = lib.options.create {
+      type = lib.types.attrs.lazy lib.types.raw;
+      default.value = builtins.mapAttrs config.configBuilders.darwin config.configurations.darwin;
+    };
+    homeConfigurations = lib.options.create {
+      type = lib.types.attrs.lazy lib.types.raw;
+      default.value = builtins.mapAttrs config.configBuilders.home config.configurations.home;
+    };
+  };
+}
diff --git a/modules/nilla/default.nix b/modules/nilla/default.nix
index 0cab965..71aed0d 100644
--- a/modules/nilla/default.nix
+++ b/modules/nilla/default.nix
@@ -2,7 +2,7 @@
   includes = [
     ./builders
     ./services.nix
-    ./systems.nix
+    ./configurations.nix
     ./modules.nix
     ./flake.nix
   ];
diff --git a/modules/nilla/flake.nix b/modules/nilla/flake.nix
index 0193f2d..f3fe6f1 100644
--- a/modules/nilla/flake.nix
+++ b/modules/nilla/flake.nix
@@ -18,12 +18,11 @@ in
       nixosModules
       darwinModules
       homeModules
+      nixosConfigurations
+      darwinConfigurations
+      homeConfigurations
       ;
 
-    nixosConfigurations = builtins.mapAttrs (_: system: system.result) config.systems.nixos;
-    darwinConfigurations = builtins.mapAttrs (_: system: system.result) config.systems.darwin;
-    homeConfigurations = builtins.mapAttrs (_: system: system.result) config.systems.home;
-
     devShells = transpose config.shells;
     packages = transpose config.packages;
 
diff --git a/modules/nilla/systems.nix b/modules/nilla/systems.nix
deleted file mode 100644
index 63b349a..0000000
--- a/modules/nilla/systems.nix
+++ /dev/null
@@ -1,52 +0,0 @@
-{ config, lib }:
-let
-  mkBuilderOption =
-    typ:
-    lib.options.create {
-      type = lib.types.function (lib.types.function lib.types.raw);
-      default.value = _name: _module: throw "Builder for systems.${typ} is not implemented";
-    };
-  inherit (config.systems) builders;
-  mkSystemModule =
-    typ:
-    { config, name }:
-    {
-      options = {
-        name = lib.options.create {
-          type = lib.types.string;
-          default.value = name;
-        };
-        module = lib.options.create {
-          type = lib.types.raw;
-          default.value = { };
-        };
-        builder = lib.options.create {
-          type = lib.types.function (lib.types.function lib.types.raw);
-          default.value = builders.${typ};
-        };
-        result = lib.options.create {
-          type = lib.types.raw;
-          writable = false;
-          default.value = config.builder config.name config.module;
-        };
-      };
-    };
-  mkSystemOption =
-    typ:
-    lib.options.create {
-      type = lib.types.attrs.of (lib.types.submodule (mkSystemModule typ));
-      default.value = { };
-    };
-in
-{
-  options = {
-    systems = {
-      builders.nixos = mkBuilderOption "nixos";
-      builders.darwin = mkBuilderOption "darwin";
-      builders.home = mkBuilderOption "home";
-      nixos = mkSystemOption "nixos";
-      darwin = mkSystemOption "darwin";
-      home = mkSystemOption "home";
-    };
-  };
-}
diff --git a/nilla.nix b/nilla.nix
index 4379f29..bc20103 100644
--- a/nilla.nix
+++ b/nilla.nix
@@ -76,42 +76,6 @@
             in
             eval.config.build.wrapper;
         };
-        ci-check =
-          let
-            all-packages = builtins.attrValues (builtins.removeAttrs config.packages [ "ci-check" ]);
-            all-packages' = lib.lists.flatten (map (pkg: builtins.attrValues pkg.result) all-packages);
-
-            nixos-systems = builtins.attrValues config.systems.nixos;
-            nixos-systems' = map (system: system.result.config.system.build.toplevel) nixos-systems;
-
-            darwin-systems = builtins.attrValues config.systems.darwin;
-            darwin-systems' = map (system: system.result.config.system.build.toplevel) darwin-systems;
-
-            all-drvs = all-packages' ++ nixos-systems' ++ darwin-systems';
-            all-drvs' = lib.strings.concatMapSep "\n" builtins.unsafeDiscardStringContext all-drvs;
-          in
-          mkPackage (
-            {
-              lib,
-              stdenvNoCC,
-              system,
-            }:
-            stdenvNoCC.mkDerivation {
-              name = "nilla-eval-check";
-              src = lib.cleanSource ./.;
-              doCheck = true;
-
-              allDerivations = all-drvs';
-              formatter = lib.getExe config.packages.formatter.result.${system};
-
-              passAsFile = [ "allDerivations" ];
-
-              installPhase = ''touch "$out"'';
-              checkPhase = ''
-                "$formatter" --ci
-              '';
-            }
-          );
       };
 
     config.shells.default = {