diff --git a/.github/workflows/nix.yml b/.github/workflows/nix.yml
index f4d6da1..03f63cb 100644
--- a/.github/workflows/nix.yml
+++ b/.github/workflows/nix.yml
@@ -14,6 +14,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu, macos]
+        eigen: ["", "-eigen_5"]
     steps:
       - uses: actions/checkout@v6
       - uses: cachix/install-nix-action@v31
@@ -21,7 +22,7 @@ jobs:
         with:
           name: gepetto
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-      - run: nix build -L
+      - run: nix build -L ".#nanoeigenpy${{ matrix.eigen }}"
 
   check:
     if: always()
diff --git a/flake.lock b/flake.lock
index 25475b1..af6b400 100644
--- a/flake.lock
+++ b/flake.lock
@@ -5,11 +5,11 @@
         "nixpkgs-lib": "nixpkgs-lib"
       },
       "locked": {
-        "lastModified": 1754487366,
-        "narHash": "sha256-pHYj8gUBapuUzKV/kN/tR3Zvqc7o6gdFB9XKXIp1SQ8=",
+        "lastModified": 1765835352,
+        "narHash": "sha256-XswHlK/Qtjasvhd1nOa1e8MgZ8GS//jBoTqWtrS1Giw=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "af66ad14b28a127c5c0f3bbb298218fc63528a18",
+        "rev": "a34fae9c08a15ad73f295041fec82323541400a9",
         "type": "github"
       },
       "original": {
@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1756266583,
-        "narHash": "sha256-cr748nSmpfvnhqSXPiCfUPxRz2FJnvf/RjJGvFfaCsM=",
+        "lastModified": 1766131741,
+        "narHash": "sha256-Rj6PPGGhYdlKWqYyqZmFHgUs5i2KEVq/zpHHwp4kR9A=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8a6d5427d99ec71c64f0b93d45778c889005d9c2",
+        "rev": "cd81579bbcc2d6885fa0c5cf8416e3bf8bf3e27e",
         "type": "github"
       },
       "original": {
@@ -36,11 +36,11 @@
     },
     "nixpkgs-lib": {
       "locked": {
-        "lastModified": 1753579242,
-        "narHash": "sha256-zvaMGVn14/Zz8hnp4VWT9xVnhc8vuL3TStRqwk22biA=",
+        "lastModified": 1765674936,
+        "narHash": "sha256-k00uTP4JNfmejrCLJOwdObYC9jHRrr/5M/a/8L2EIdo=",
         "owner": "nix-community",
         "repo": "nixpkgs.lib",
-        "rev": "0f36c44e01a6129be94e3ade315a5883f0228a6e",
+        "rev": "2075416fcb47225d9b68ac469a5c4801a9c4dd85",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 94a6735..406fb82 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,26 +8,65 @@
 
   outputs =
     inputs:
-    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
-      systems = inputs.nixpkgs.lib.systems.flakeExposed;
-      perSystem =
-        { pkgs, self', ... }:
-        {
-          packages = {
-            default = self'.packages.nanoeigenpy;
-            nanoeigenpy = pkgs.python3Packages.nanoeigenpy.overrideAttrs (_: {
-              src = pkgs.lib.fileset.toSource {
-                root = ./.;
-                fileset = pkgs.lib.fileset.unions [
-                  ./CMakeLists.txt
-                  ./include
-                  ./package.xml
-                  ./src
-                  ./tests
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } (
+      { self, lib, ... }:
+      {
+        systems = inputs.nixpkgs.lib.systems.flakeExposed;
+        flake.overlays = {
+          default = final: prev: {
+            pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [
+              (python-final: python-prev: {
+                eigenpy = python-prev.eigenpy.overrideAttrs {
+                  src = lib.fileset.toSource {
+                    root = ./.;
+                    fileset = lib.fileset.unions [
+                      ./CMakeLists.txt
+                      ./include
+                      ./package.xml
+                      ./src
+                      ./tests
+                    ];
+                  };
+                };
+              })
+            ];
+          };
+          eigen_5 = final: _prev: {
+            eigen = final.eigen_5;
+          };
+        };
+        perSystem =
+          {
+            pkgs,
+            pkgs-eigen_5,
+            self',
+            system,
+            ...
+          }:
+          {
+            _module.args = {
+              pkgs = import inputs.nixpkgs {
+                inherit system;
+                overlays = [ self.overlays.default ];
+              };
+              pkgs-eigen_5 = import inputs.nixpkgs {
+                inherit system;
+                overlays = [
+                  self.overlays.eigen_5
+                  self.overlays.default
                 ];
               };
-            });
+            };
+            apps.default = {
+              type = "app";
+              program = pkgs.python3.withPackages (_: [ self'.packages.default ]);
+            };
+            packages = {
+              default = self'.packages.nanoeigenpy;
+              nanoeigenpy = pkgs.python3Packages.nanoeigenpy;
+              nanoeigenpy-eigen_5 = pkgs-eigen_5.python3Packages.nanoeigenpy;
+            };
           };
-        };
-    };
+      }
+    );
 }