diff --git a/.github/workflows/nix.yml b/.github/workflows/nix.yml
index 3888180cb..8cf2d6cac 100644
--- a/.github/workflows/nix.yml
+++ b/.github/workflows/nix.yml
@@ -21,7 +21,21 @@ jobs:
         with:
           name: gepetto
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-      - run: nix build -L
+      - run: nix build -L .#proxsuite
+
+  nix-eigen5:
+    runs-on: "${{ matrix.os }}"
+    strategy:
+      matrix:
+        os: ["ubuntu-24.04", "macos-15"]
+    steps:
+      - uses: actions/checkout@v5
+      - uses: cachix/install-nix-action@v31
+      - uses: cachix/cachix-action@v16
+        with:
+          name: gepetto
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+      - run: nix build -L .#proxsuite-eigen_5
 
   check:
     if: always()
@@ -29,6 +43,7 @@ jobs:
 
     needs:
       - nix
+      - nix-eigen5
 
     runs-on: Ubuntu-latest
 
diff --git a/flake.lock b/flake.lock
index 1d82371db..0f5320e17 100644
--- a/flake.lock
+++ b/flake.lock
@@ -5,11 +5,11 @@
         "nixpkgs-lib": "nixpkgs-lib"
       },
       "locked": {
-        "lastModified": 1749398372,
-        "narHash": "sha256-tYBdgS56eXYaWVW3fsnPQ/nFlgWi/Z2Ymhyu21zVM98=",
+        "lastModified": 1760948891,
+        "narHash": "sha256-TmWcdiUUaWk8J4lpjzu4gCGxWY6/Ok7mOK4fIFfBuU4=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "9305fe4e5c2a6fcf5ba6a3ff155720fbe4076569",
+        "rev": "864599284fc7c0ba6357ed89ed5e2cd5040f0c04",
         "type": "github"
       },
       "original": {
@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1750134718,
-        "narHash": "sha256-v263g4GbxXv87hMXMCpjkIxd/viIF7p3JpJrwgKdNiI=",
+        "lastModified": 1761373498,
+        "narHash": "sha256-Q/uhWNvd7V7k1H1ZPMy/vkx3F8C13ZcdrKjO7Jv7v0c=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "9e83b64f727c88a7711a2c463a7b16eedb69a84c",
+        "rev": "6a08e6bb4e46ff7fcbb53d409b253f6bad8a28ce",
         "type": "github"
       },
       "original": {
@@ -36,11 +36,11 @@
     },
     "nixpkgs-lib": {
       "locked": {
-        "lastModified": 1748740939,
-        "narHash": "sha256-rQaysilft1aVMwF14xIdGS3sj1yHlI6oKQNBRTF40cc=",
+        "lastModified": 1754788789,
+        "narHash": "sha256-x2rJ+Ovzq0sCMpgfgGaaqgBSwY+LST+WbZ6TytnT9Rk=",
         "owner": "nix-community",
         "repo": "nixpkgs.lib",
-        "rev": "656a64127e9d791a334452c6b6606d17539476e2",
+        "rev": "a73b9c743612e4244d865a2fdee11865283c04e6",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index e16df8d7c..c40004f35 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,21 +8,16 @@
 
   outputs =
     inputs:
-    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
-      systems = inputs.nixpkgs.lib.systems.flakeExposed;
-      perSystem =
-        { pkgs, self', ... }:
-        {
-          apps.default = {
-            type = "app";
-            program = pkgs.python3.withPackages (_: [ self'.packages.default ]);
-          };
-          packages = {
-            default = self'.packages.proxsuite;
-            proxsuite = pkgs.python3Packages.proxsuite.overrideAttrs {
-              src = pkgs.lib.fileset.toSource {
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } (
+      { self, lib, ... }:
+      {
+        systems = inputs.nixpkgs.lib.systems.flakeExposed;
+        flake.overlays = {
+          default = final: prev: {
+            proxsuite = prev.proxsuite.overrideAttrs {
+              src = lib.fileset.toSource {
                 root = ./.;
-                fileset = pkgs.lib.fileset.unions [
+                fileset = lib.fileset.unions [
                   ./benchmark
                   ./bindings
                   ./cmake-external
@@ -34,8 +29,65 @@
                   ./test
                 ];
               };
+              postPatch = "";
+              nativeCheckInputs = [
+                final.ctestCheckHook
+              ];
+              # ref. https://github.com/Simple-Robotics/proxsuite/issues/426
+              preCheck = ''
+                disabledTests+=(
+                  "ProxQP::dense: test primal infeasibility solving"
+                  "dense maros meszaros using the api"
+                  "sparse maros meszaros using the API"
+                )
+              '';
             };
           };
+          eigen5 = final: prev: {
+            eigen = prev.eigen.overrideAttrs (super: rec {
+              version = "5.0.0";
+              src = final.fetchFromGitLab {
+                inherit (super.src) owner repo;
+                tag = version;
+                hash = "sha256-L1KUFZsaibC/FD6abTXrT3pvaFhbYnw+GaWsxM2gaxM=";
+              };
+              patches = [ ];
+              postPatch = "";
+            });
+          };
         };
-    };
+        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.eigen5
+                  self.overlays.default
+                ];
+              };
+            };
+            apps.default = {
+              type = "app";
+              program = pkgs.python3.withPackages (_: [ self'.packages.default ]);
+            };
+            packages = {
+              default = self'.packages.proxsuite;
+              proxsuite = pkgs.python3Packages.proxsuite;
+              proxsuite-eigen_5 = pkgs-eigen_5.python3Packages.proxsuite;
+            };
+          };
+      }
+    );
 }