diff --git a/ci.nix b/ci.nix
deleted file mode 100644
index 2687cdf..0000000
--- a/ci.nix
+++ /dev/null
@@ -1,35 +0,0 @@
-# SPDX-FileCopyrightText: 2021 Serokell <https://serokell.io>
-#
-# SPDX-License-Identifier: MPL-2.0
-
-rec {
-  sources = import ./nix/sources.nix;
-  haskell-nix = import sources."haskell.nix" {
-    sourcesOverride = { hackage = sources."hackage.nix"; stackage = sources."stackage.nix"; };
-  };
-  serokell-nix = import sources."serokell.nix";
-  pkgs = import sources.nixpkgs (
-    haskell-nix.nixpkgsArgs // {
-      overlays =
-        haskell-nix.nixpkgsArgs.overlays
-        ++ [ serokell-nix.overlay ]; # contains trailing whitespace check
-    }
-  );
-
-  project-src = pkgs.haskell-nix.haskellLib.cleanGit {
-    name = "xrefcheck";
-    src = pkgs.haskell-nix.haskellLib.cleanSourceWith {
-      filter = path: type: !(pkgs.lib.hasInfix "tests/golden/helpers" path);
-      src = ./.;
-    };
-  };
-
-  # TODO: drop this when `serokell/nixpkgs` acquires stylish-haskell >= 0.13.0.0.
-  pkgs-stylish = import sources.nixpkgs-stylish {};
-
-  xrefcheck-lib-and-tests = (import ./xrefcheck.nix { linux = true; });
-  xrefcheck-static = (import ./xrefcheck.nix { linux-static = true; }).components.exes.xrefcheck;
-  xrefcheck-windows = (import ./xrefcheck.nix { windows = true; }).components.exes.xrefcheck;
-
-  trailing-whitespace-check = pkgs.build.checkTrailingWhitespace project-src;
-}
diff --git a/default.nix b/default.nix
index 231843c..f377d6e 100644
--- a/default.nix
+++ b/default.nix
@@ -1,7 +1,14 @@
-# SPDX-FileCopyrightText: 2019 Serokell <https://serokell.io>
-#
+# SPDX-FileCopyrightText: 2023 Serokell <https://serokell.io>
 # SPDX-License-Identifier: MPL-2.0
 
-{ platform ? "linux-static" }:
-
-(import ./xrefcheck.nix { ${platform} = true; }).components.exes.xrefcheck
+let
+  inherit (import
+  (let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    })
+  { src = ./.; }) defaultNix;
+  system = builtins.currentSystem;
+in defaultNix //
+   (defaultNix.legacyPackages.${system}.lib.attrsets.mapAttrs (_: val: val.${system}) defaultNix)
diff --git a/docker/default.nix b/docker/default.nix
deleted file mode 100644
index 9404c87..0000000
--- a/docker/default.nix
+++ /dev/null
@@ -1,18 +0,0 @@
-# SPDX-FileCopyrightText: 2020 Serokell <https://serokell.io>
-#
-# SPDX-License-Identifier: MPL-2.0
-
-{ pkgs ? import (import ../nix/sources.nix).nixpkgs { } }:
-let
-  executable =
-    (import ../xrefcheck.nix { linux-static = true; }).components.exes.xrefcheck;
-  binOnly = pkgs.runCommand "xrefcheck-bin" { } ''
-    mkdir -p $out/bin
-    cp ${executable}/bin/xrefcheck $out/bin
-    ${pkgs.nukeReferences}/bin/nuke-refs $out/bin/xrefcheck
-  '';
-in pkgs.dockerTools.buildImage {
-  name = "xrefcheck";
-  contents = [ binOnly pkgs.cacert ];
-  config.Entrypoint = "xrefcheck";
-}
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..d35cda7
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,1091 @@
+{
+  "nodes": {
+    "HTTP": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1451647621,
+        "narHash": "sha256-oHIyw3x0iKBexEo49YeUDV1k74ZtyYKGR2gNJXXRxts=",
+        "owner": "phadej",
+        "repo": "HTTP",
+        "rev": "9bc0996d412fef1787449d841277ef663ad9a915",
+        "type": "github"
+      },
+      "original": {
+        "owner": "phadej",
+        "repo": "HTTP",
+        "type": "github"
+      }
+    },
+    "blank": {
+      "locked": {
+        "lastModified": 1625557891,
+        "narHash": "sha256-O8/MWsPBGhhyPoPLHZAuoZiiHo9q6FLlEeIDEXuj6T4=",
+        "owner": "divnix",
+        "repo": "blank",
+        "rev": "5a5d2684073d9f563072ed07c871d577a6c614a8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "divnix",
+        "repo": "blank",
+        "type": "github"
+      }
+    },
+    "cabal-32": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1603716527,
+        "narHash": "sha256-X0TFfdD4KZpwl0Zr6x+PLxUt/VyKQfX7ylXHdmZIL+w=",
+        "owner": "haskell",
+        "repo": "cabal",
+        "rev": "48bf10787e27364730dd37a42b603cee8d6af7ee",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "3.2",
+        "repo": "cabal",
+        "type": "github"
+      }
+    },
+    "cabal-34": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1640353650,
+        "narHash": "sha256-N1t6M3/wqj90AEdRkeC8i923gQYUpzSr8b40qVOZ1Rk=",
+        "owner": "haskell",
+        "repo": "cabal",
+        "rev": "942639c18c0cd8ec53e0a6f8d120091af35312cd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "3.4",
+        "repo": "cabal",
+        "type": "github"
+      }
+    },
+    "cabal-36": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1641652457,
+        "narHash": "sha256-BlFPKP4C4HRUJeAbdembX1Rms1LD380q9s0qVDeoAak=",
+        "owner": "haskell",
+        "repo": "cabal",
+        "rev": "f27667f8ec360c475027dcaee0138c937477b070",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "3.6",
+        "repo": "cabal",
+        "type": "github"
+      }
+    },
+    "cardano-shell": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1608537748,
+        "narHash": "sha256-PulY1GfiMgKVnBci3ex4ptk2UNYMXqGjJOxcPy2KYT4=",
+        "owner": "input-output-hk",
+        "repo": "cardano-shell",
+        "rev": "9392c75087cb9a3d453998f4230930dea3a95725",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "cardano-shell",
+        "type": "github"
+      }
+    },
+    "deploy-rs": {
+      "inputs": {
+        "flake-compat": "flake-compat_3",
+        "nixpkgs": "nixpkgs_5",
+        "utils": "utils_2"
+      },
+      "locked": {
+        "lastModified": 1648475189,
+        "narHash": "sha256-gAGAS6IagwoUr1B0ohE3iR6sZ8hP4LSqzYLC8Mq3WGU=",
+        "owner": "serokell",
+        "repo": "deploy-rs",
+        "rev": "83e0c78291cd08cb827ba0d553ad9158ae5a95c3",
+        "type": "github"
+      },
+      "original": {
+        "id": "deploy-rs",
+        "type": "indirect"
+      }
+    },
+    "devshell": {
+      "inputs": {
+        "flake-utils": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1663445644,
+        "narHash": "sha256-+xVlcK60x7VY1vRJbNUEAHi17ZuoQxAIH4S4iUFUGBA=",
+        "owner": "numtide",
+        "repo": "devshell",
+        "rev": "e3dc3e21594fe07bdb24bdf1c8657acaa4cb8f66",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "devshell",
+        "type": "github"
+      }
+    },
+    "dmerge": {
+      "inputs": {
+        "nixlib": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "nixpkgs"
+        ],
+        "yants": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "yants"
+        ]
+      },
+      "locked": {
+        "lastModified": 1659548052,
+        "narHash": "sha256-fzI2gp1skGA8mQo/FBFrUAtY0GQkAIAaV/V127TJPyY=",
+        "owner": "divnix",
+        "repo": "data-merge",
+        "rev": "d160d18ce7b1a45b88344aa3f13ed1163954b497",
+        "type": "github"
+      },
+      "original": {
+        "owner": "divnix",
+        "repo": "data-merge",
+        "type": "github"
+      }
+    },
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1635892615,
+        "narHash": "sha256-harGbMZr4hzat2BWBU+Y5OYXlu+fVz7E4WeQzHi5o8A=",
+        "owner": "input-output-hk",
+        "repo": "flake-compat",
+        "rev": "eca47d3377946315596da653862d341ee5341318",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-compat_2": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1650374568,
+        "narHash": "sha256-Z+s0J8/r907g149rllvwhb4pKi8Wam5ij0st8PwAh+E=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "b4a34015c698c7793d592d66adbab377907a2be8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-compat_3": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1648199409,
+        "narHash": "sha256-JwPKdC2PoVBkG6E+eWw3j6BMR6sL3COpYWfif7RVb8Y=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "64a525ee38886ab9028e6f61790de0832aa3ef03",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
+    "flake-compat_4": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1627913399,
+        "narHash": "sha256-hY8g6H2KFL8ownSiFeMOjwPC8P0ueXpCVEbxgda3pko=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "12c64ca55c1014cdc1b16ed5a804aa8576601ff2",
+        "type": "github"
+      },
+      "original": {
+        "id": "flake-compat",
+        "type": "indirect"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "id": "flake-utils",
+        "type": "indirect"
+      }
+    },
+    "flake-utils_2": {
+      "locked": {
+        "lastModified": 1644229661,
+        "narHash": "sha256-1YdnJAsNy69bpcjuoKdOYQX0YxZBiCYZo4Twxerqv7k=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "3cecb5b042f7f209c56ffd8371b2711a290ec797",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_3": {
+      "locked": {
+        "lastModified": 1653893745,
+        "narHash": "sha256-0jntwV3Z8//YwuOjzhV2sgJJPt+HY6KhU7VZUL0fKZQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ed9fb1935d260de5fe1c2f7ee0ebaae17ed2fa1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_4": {
+      "locked": {
+        "lastModified": 1659877975,
+        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_5": {
+      "locked": {
+        "lastModified": 1653893745,
+        "narHash": "sha256-0jntwV3Z8//YwuOjzhV2sgJJPt+HY6KhU7VZUL0fKZQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ed9fb1935d260de5fe1c2f7ee0ebaae17ed2fa1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_6": {
+      "locked": {
+        "lastModified": 1631561581,
+        "narHash": "sha256-3VQMV5zvxaVLvqqUrNz3iJelLw30mIVSfZmAaauM3dA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "7e5bf3925f6fbdfaf50a2a7ca0be2879c4261d19",
+        "type": "github"
+      },
+      "original": {
+        "id": "flake-utils",
+        "type": "indirect"
+      }
+    },
+    "ghc-8.6.5-iohk": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1600920045,
+        "narHash": "sha256-DO6kxJz248djebZLpSzTGD6s8WRpNI9BTwUeOf5RwY8=",
+        "owner": "input-output-hk",
+        "repo": "ghc",
+        "rev": "95713a6ecce4551240da7c96b6176f980af75cae",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "ref": "release/8.6.5-iohk",
+        "repo": "ghc",
+        "type": "github"
+      }
+    },
+    "gitignore-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1611672876,
+        "narHash": "sha256-qHu3uZ/o9jBHiA3MEKHJ06k7w4heOhA+4HCSIvflRxo=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "211907489e9f198594c0eb0ca9256a1949c9d412",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "gomod2nix": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_2",
+        "utils": "utils"
+      },
+      "locked": {
+        "lastModified": 1655245309,
+        "narHash": "sha256-d/YPoQ/vFn1+GTmSdvbSBSTOai61FONxB4+Lt6w/IVI=",
+        "owner": "tweag",
+        "repo": "gomod2nix",
+        "rev": "40d32f82fc60d66402eb0972e6e368aeab3faf58",
+        "type": "github"
+      },
+      "original": {
+        "owner": "tweag",
+        "repo": "gomod2nix",
+        "type": "github"
+      }
+    },
+    "hackage": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1671150792,
+        "narHash": "sha256-X9u0eAQTxJacvrB1ET0CPlZpF5nD+ahWp2vaPrFo+HY=",
+        "owner": "input-output-hk",
+        "repo": "hackage.nix",
+        "rev": "21c41f38fd29f753c0525e5adf2c9ec128719515",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "hackage.nix",
+        "type": "github"
+      }
+    },
+    "haskell-nix": {
+      "inputs": {
+        "HTTP": "HTTP",
+        "cabal-32": "cabal-32",
+        "cabal-34": "cabal-34",
+        "cabal-36": "cabal-36",
+        "cardano-shell": "cardano-shell",
+        "flake-compat": "flake-compat",
+        "flake-utils": "flake-utils_2",
+        "ghc-8.6.5-iohk": "ghc-8.6.5-iohk",
+        "hackage": "hackage",
+        "hpc-coveralls": "hpc-coveralls",
+        "hydra": "hydra",
+        "iserv-proxy": "iserv-proxy",
+        "nixpkgs": [
+          "haskell-nix",
+          "nixpkgs-unstable"
+        ],
+        "nixpkgs-2003": "nixpkgs-2003",
+        "nixpkgs-2105": "nixpkgs-2105",
+        "nixpkgs-2111": "nixpkgs-2111",
+        "nixpkgs-2205": "nixpkgs-2205",
+        "nixpkgs-2211": "nixpkgs-2211",
+        "nixpkgs-unstable": "nixpkgs-unstable",
+        "old-ghc-nix": "old-ghc-nix",
+        "stackage": "stackage",
+        "tullia": "tullia"
+      },
+      "locked": {
+        "lastModified": 1671151873,
+        "narHash": "sha256-9nisAyp2nusKqvtvps4Uc+I/HPcpbgXkH5qnfqAjsio=",
+        "owner": "input-output-hk",
+        "repo": "haskell.nix",
+        "rev": "2860f6c26b6c2672b4ed34216efd26a2eb96dd4e",
+        "type": "github"
+      },
+      "original": {
+        "id": "haskell-nix",
+        "type": "indirect"
+      }
+    },
+    "hpc-coveralls": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1607498076,
+        "narHash": "sha256-8uqsEtivphgZWYeUo5RDUhp6bO9j2vaaProQxHBltQk=",
+        "owner": "sevanspowell",
+        "repo": "hpc-coveralls",
+        "rev": "14df0f7d229f4cd2e79f8eabb1a740097fdfa430",
+        "type": "github"
+      },
+      "original": {
+        "owner": "sevanspowell",
+        "repo": "hpc-coveralls",
+        "type": "github"
+      }
+    },
+    "hydra": {
+      "inputs": {
+        "nix": "nix",
+        "nixpkgs": [
+          "haskell-nix",
+          "hydra",
+          "nix",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1646878427,
+        "narHash": "sha256-KtbrofMtN8GlM7D+n90kixr7QpSlVmdN+vK5CA/aRzc=",
+        "owner": "NixOS",
+        "repo": "hydra",
+        "rev": "28b682b85b7efc5cf7974065792a1f22203a5927",
+        "type": "github"
+      },
+      "original": {
+        "id": "hydra",
+        "type": "indirect"
+      }
+    },
+    "iserv-proxy": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1639165170,
+        "narHash": "sha256-QsWL/sBDL5GM8IXd/dE/ORiL4RvteEN+aok23tXgAoc=",
+        "rev": "6e95df7be6dd29680f983db07a057fc2f34f81f6",
+        "revCount": 7,
+        "type": "git",
+        "url": "https://gitlab.haskell.org/ghc/iserv-proxy.git"
+      },
+      "original": {
+        "rev": "6e95df7be6dd29680f983db07a057fc2f34f81f6",
+        "type": "git",
+        "url": "https://gitlab.haskell.org/ghc/iserv-proxy.git"
+      }
+    },
+    "lowdown-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1633514407,
+        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "type": "github"
+      }
+    },
+    "lowdown-src_2": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1632468475,
+        "narHash": "sha256-NNOm9CbdA8cuwbvaBHslGbPTiU6bh1Ao+MpEPx4rSGo=",
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "rev": "6bd668af3fd098bdd07a1bedd399564141e275da",
+        "type": "github"
+      },
+      "original": {
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "type": "github"
+      }
+    },
+    "mdbook-kroki-preprocessor": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1661755005,
+        "narHash": "sha256-1TJuUzfyMycWlOQH67LR63/ll2GDZz25I3JfScy/Jnw=",
+        "owner": "JoelCourtney",
+        "repo": "mdbook-kroki-preprocessor",
+        "rev": "93adb5716d035829efed27f65f2f0833a7d3e76f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "JoelCourtney",
+        "repo": "mdbook-kroki-preprocessor",
+        "type": "github"
+      }
+    },
+    "n2c": {
+      "inputs": {
+        "flake-utils": "flake-utils_5",
+        "nixpkgs": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1665039323,
+        "narHash": "sha256-SAh3ZjFGsaCI8FRzXQyp56qcGdAqgKEfJWPCQ0Sr7tQ=",
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "rev": "b008fe329ffb59b67bf9e7b08ede6ee792f2741a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "type": "github"
+      }
+    },
+    "nix": {
+      "inputs": {
+        "lowdown-src": "lowdown-src",
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-regression": "nixpkgs-regression"
+      },
+      "locked": {
+        "lastModified": 1643066034,
+        "narHash": "sha256-xEPeMcNJVOeZtoN+d+aRwolpW8mFSEQx76HTRdlhPhg=",
+        "owner": "NixOS",
+        "repo": "nix",
+        "rev": "a1cd7e58606a41fcf62bf8637804cf8306f17f62",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "2.6.0",
+        "repo": "nix",
+        "type": "github"
+      }
+    },
+    "nix-nomad": {
+      "inputs": {
+        "flake-compat": "flake-compat_2",
+        "flake-utils": [
+          "haskell-nix",
+          "tullia",
+          "nix2container",
+          "flake-utils"
+        ],
+        "gomod2nix": "gomod2nix",
+        "nixpkgs": [
+          "haskell-nix",
+          "tullia",
+          "nixpkgs"
+        ],
+        "nixpkgs-lib": [
+          "haskell-nix",
+          "tullia",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1658277770,
+        "narHash": "sha256-T/PgG3wUn8Z2rnzfxf2VqlR1CBjInPE0l1yVzXxPnt0=",
+        "owner": "tristanpemble",
+        "repo": "nix-nomad",
+        "rev": "054adcbdd0a836ae1c20951b67ed549131fd2d70",
+        "type": "github"
+      },
+      "original": {
+        "owner": "tristanpemble",
+        "repo": "nix-nomad",
+        "type": "github"
+      }
+    },
+    "nix2container": {
+      "inputs": {
+        "flake-utils": "flake-utils_3",
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1658567952,
+        "narHash": "sha256-XZ4ETYAMU7XcpEeAFP3NOl9yDXNuZAen/aIJ84G+VgA=",
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "rev": "60bb43d405991c1378baf15a40b5811a53e32ffa",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nlewo",
+        "repo": "nix2container",
+        "type": "github"
+      }
+    },
+    "nix_2": {
+      "inputs": {
+        "lowdown-src": "lowdown-src_2",
+        "nixpkgs": "nixpkgs_6"
+      },
+      "locked": {
+        "lastModified": 1633098935,
+        "narHash": "sha256-UtuBczommNLwUNEnfRI7822z4vPA7OoRKsgAZ8zsHQI=",
+        "owner": "nixos",
+        "repo": "nix",
+        "rev": "4f496150eb4e0012914c11f0a3ff4df2412b1d09",
+        "type": "github"
+      },
+      "original": {
+        "id": "nix",
+        "type": "indirect"
+      }
+    },
+    "nixago": {
+      "inputs": {
+        "flake-utils": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "flake-utils"
+        ],
+        "nixago-exts": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "blank"
+        ],
+        "nixpkgs": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1661824785,
+        "narHash": "sha256-/PnwdWoO/JugJZHtDUioQp3uRiWeXHUdgvoyNbXesz8=",
+        "owner": "nix-community",
+        "repo": "nixago",
+        "rev": "8c1f9e5f1578d4b2ea989f618588d62a335083c3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nixago",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1632864508,
+        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-21.05-small",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs-2003": {
+      "locked": {
+        "lastModified": 1620055814,
+        "narHash": "sha256-8LEHoYSJiL901bTMVatq+rf8y7QtWuZhwwpKE2fyaRY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "1db42b7fe3878f3f5f7a4f2dc210772fd080e205",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-20.03-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-2105": {
+      "locked": {
+        "lastModified": 1659914493,
+        "narHash": "sha256-lkA5X3VNMKirvA+SUzvEhfA7XquWLci+CGi505YFAIs=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "022caabb5f2265ad4006c1fa5b1ebe69fb0c3faf",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-21.05-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-2111": {
+      "locked": {
+        "lastModified": 1659446231,
+        "narHash": "sha256-hekabNdTdgR/iLsgce5TGWmfIDZ86qjPhxDg/8TlzhE=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "eabc38219184cc3e04a974fe31857d8e0eac098d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-21.11-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-2205": {
+      "locked": {
+        "lastModified": 1663981975,
+        "narHash": "sha256-TKaxWAVJR+a5JJauKZqibmaM5e/Pi5tBDx9s8fl/kSE=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "309faedb8338d3ae8ad8f1043b3ccf48c9cc2970",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-22.05-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-2211": {
+      "locked": {
+        "lastModified": 1669997163,
+        "narHash": "sha256-vhjC0kZMFoN6jzK0GR+tBzKi5KgBXgehadfidW8+Va4=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "6f87491a54d8d64d30af6663cb3bf5d2ee7db958",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-22.11-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-regression": {
+      "locked": {
+        "lastModified": 1643052045,
+        "narHash": "sha256-uGJ0VXIhWKGXxkeNnq4TvV3CIOkUJ3PAoLZ3HMzNVMw=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1663905476,
+        "narHash": "sha256-0CSwRKaYravh9v6qSlBpM0gNg0UhKT2lL7Yn6Zbx7UM=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e14f9fb57315f0d4abde222364f19f88c77d2b79",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1653581809,
+        "narHash": "sha256-Uvka0V5MTGbeOfWte25+tfRL3moECDh1VwokWSZUdoY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "83658b28fe638a170a19b8933aa008b30640fbd1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1654807842,
+        "narHash": "sha256-ADymZpr6LuTEBXcy6RtFHcUZdjKTBRTMYwu19WOx17E=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "fc909087cc3386955f21b4665731dbdaceefb1d8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_4": {
+      "locked": {
+        "lastModified": 1665087388,
+        "narHash": "sha256-FZFPuW9NWHJteATOf79rZfwfRn5fE0wi9kRzvGfDHPA=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "95fda953f6db2e9496d2682c4fc7b82f959878f7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_5": {
+      "locked": {
+        "lastModified": 1648219316,
+        "narHash": "sha256-Ctij+dOi0ZZIfX5eMhgwugfvB+WZSrvVNAyAuANOsnQ=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "30d3d79b7d3607d56546dd2a6b49e156ba0ec634",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_6": {
+      "locked": {
+        "lastModified": 1632864508,
+        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-21.05-small",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_7": {
+      "locked": {
+        "lastModified": 1667318090,
+        "narHash": "sha256-AvxgT+t1BWZs8IfdseHl8+7wvWWm9pvysupMT9wXdH0=",
+        "owner": "serokell",
+        "repo": "nixpkgs",
+        "rev": "4bce79cf151aad3c0bed46a32bdb4b165f00cb7e",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "old-ghc-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1631092763,
+        "narHash": "sha256-sIKgO+z7tj4lw3u6oBZxqIhDrzSkvpHtv0Kki+lh9Fg=",
+        "owner": "angerman",
+        "repo": "old-ghc-nix",
+        "rev": "af48a7a7353e418119b6dfe3cd1463a657f342b8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "angerman",
+        "ref": "master",
+        "repo": "old-ghc-nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "haskell-nix": "haskell-nix",
+        "serokell-nix": "serokell-nix"
+      }
+    },
+    "serokell-nix": {
+      "inputs": {
+        "deploy-rs": "deploy-rs",
+        "flake-compat": "flake-compat_4",
+        "flake-utils": "flake-utils_6",
+        "gitignore-nix": "gitignore-nix",
+        "nix": "nix_2",
+        "nixpkgs": "nixpkgs_7"
+      },
+      "locked": {
+        "lastModified": 1671444753,
+        "narHash": "sha256-ZCRHdrewAtq+VYhF0EtSwR6Cc4qYXKobXqhmbimwP/I=",
+        "owner": "serokell",
+        "repo": "serokell.nix",
+        "rev": "f179f81b4421eb3158af2cfe062adb9fce427b17",
+        "type": "github"
+      },
+      "original": {
+        "id": "serokell-nix",
+        "type": "indirect"
+      }
+    },
+    "stackage": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1670890221,
+        "narHash": "sha256-kV7irjUr4Ot3b2MwTcgVKYuEe+legxhGh4ApBeESy1s=",
+        "owner": "input-output-hk",
+        "repo": "stackage.nix",
+        "rev": "56f59c2d4ecdb237348a0774274f38874f81a3ca",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "stackage.nix",
+        "type": "github"
+      }
+    },
+    "std": {
+      "inputs": {
+        "blank": "blank",
+        "devshell": "devshell",
+        "dmerge": "dmerge",
+        "flake-utils": "flake-utils_4",
+        "makes": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "blank"
+        ],
+        "mdbook-kroki-preprocessor": "mdbook-kroki-preprocessor",
+        "microvm": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "blank"
+        ],
+        "n2c": "n2c",
+        "nixago": "nixago",
+        "nixpkgs": "nixpkgs_4",
+        "yants": "yants"
+      },
+      "locked": {
+        "lastModified": 1665513321,
+        "narHash": "sha256-D6Pacw9yf/HMs84KYuCxHXnNDL7v43gtcka5URagFqE=",
+        "owner": "divnix",
+        "repo": "std",
+        "rev": "94a90eedb9cfc115b12ae8f6622d9904788559e4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "divnix",
+        "repo": "std",
+        "type": "github"
+      }
+    },
+    "tullia": {
+      "inputs": {
+        "nix-nomad": "nix-nomad",
+        "nix2container": "nix2container",
+        "nixpkgs": [
+          "haskell-nix",
+          "nixpkgs"
+        ],
+        "std": "std"
+      },
+      "locked": {
+        "lastModified": 1668711738,
+        "narHash": "sha256-CBjky16o9pqsGE1bWu6nRlRajgSXMEk+yaFQLibqXcE=",
+        "owner": "input-output-hk",
+        "repo": "tullia",
+        "rev": "ead1f515c251f0e060060ef0e2356a51d3dfe4b0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "tullia",
+        "type": "github"
+      }
+    },
+    "utils": {
+      "locked": {
+        "lastModified": 1653893745,
+        "narHash": "sha256-0jntwV3Z8//YwuOjzhV2sgJJPt+HY6KhU7VZUL0fKZQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ed9fb1935d260de5fe1c2f7ee0ebaae17ed2fa1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "utils_2": {
+      "locked": {
+        "lastModified": 1648297722,
+        "narHash": "sha256-W+qlPsiZd8F3XkzXOzAoR+mpFqzm3ekQkJNa+PIh1BQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "0f8662f1319ad6abf89b3380dd2722369fc51ade",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "yants": {
+      "inputs": {
+        "nixpkgs": [
+          "haskell-nix",
+          "tullia",
+          "std",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1660507851,
+        "narHash": "sha256-BKjq7JnVuUR/xDtcv6Vm9GYGKAblisXrAgybor9hT/s=",
+        "owner": "divnix",
+        "repo": "yants",
+        "rev": "0b895ca02a8fa72bad50b454cb3e7d8a66407c96",
+        "type": "github"
+      },
+      "original": {
+        "owner": "divnix",
+        "repo": "yants",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.lock.license b/flake.lock.license
new file mode 100644
index 0000000..64d2773
--- /dev/null
+++ b/flake.lock.license
@@ -0,0 +1,2 @@
+SPDX-FileCopyrightText: 2023 Serokell <https://serokell.io>
+SPDX-License-Identifier: MPL-2.0
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..0d4d27f
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,91 @@
+# SPDX-FileCopyrightText: 2023 Serokell <https://serokell.io>
+# SPDX-License-Identifier: MPL-2.0
+
+{
+  description = "The xrefcheck flake";
+
+  nixConfig.flake-registry = "https://github.com/serokell/flake-registry/raw/master/flake-registry.json";
+
+  outputs = { self, flake-utils, haskell-nix, serokell-nix, ... }:
+    flake-utils.lib.eachSystem [ "x86_64-linux" ] (system:
+    let
+      pkgs = haskell-nix.legacyPackages.${system}.extend serokell-nix.overlay;
+
+      flake = (pkgs.haskell-nix.stackProject {
+        src = ./.;
+        modules = [{
+          packages.xrefcheck = {
+            ghcOptions =
+              [ "-Werror" ];
+
+            components.tests = {
+              ftp-tests = {
+                build-tools = [ pkgs.vsftpd ];
+                preCheck = ''
+                  echo "Starting vsftpd..."
+                  touch /tmp/vsftpd.log
+                  vsftpd \
+                  -orun_as_launching_user=yes \
+                  -olisten_port=2221 \
+                  -olisten=yes \
+                  -oftp_username=$(whoami) \
+                  -oanon_root=${./ftp-tests/ftp_root} \
+                  -opasv_min_port=2222 \
+                  -ohide_file='{.*}' \
+                  -odeny_file='{.*}' \
+                  -oseccomp_sandbox=no \
+                  -olog_ftp_protocol=yes \
+                  -oxferlog_enable=yes \
+                  -ovsftpd_log_file=/tmp/vsftpd.log &
+                  sleep 1
+                  tail -f /tmp/vsftpd.log &
+                '';
+                testFlags = [ "--ftp-host" "ftp://localhost:2221" ];
+              };
+              xrefcheck-tests.build-tools = [ pkgs.git ];
+            };
+          };
+        }];
+      }).flake { crossPlatforms = p: [ p.musl64 p.mingwW64 ]; };
+
+    in
+      pkgs.lib.lists.foldr pkgs.lib.recursiveUpdate {} [
+        { inherit (flake) packages apps; }
+        {
+          legacyPackages = pkgs;
+
+          apps.default = self.apps.${system}."x86_64-unknown-linux-musl:xrefcheck:exe:xrefcheck";
+
+          packages = {
+
+            default = self.packages.${system}.xrefcheck;
+
+            xrefcheck = self.packages.${system}."xrefcheck:exe:xrefcheck";
+
+            xrefcheck-static = self.packages.${system}."x86_64-unknown-linux-musl:xrefcheck:exe:xrefcheck";
+
+            xrefcheck-windows = self.packages.${system}."x86_64-w64-mingw32:xrefcheck:exe:xrefcheck";
+
+            docker-image =
+            let
+              executable = self.packages.${system}.xrefcheck-static;
+              binOnly = pkgs.runCommand "xrefcheck-bin" {} ''
+                mkdir -p $out/bin
+                cp ${executable}/bin/xrefcheck $out/bin
+                ${pkgs.nukeReferences}/bin/nuke-refs $out/bin/xrefcheck
+              '';
+            in pkgs.dockerTools.buildImage {
+              name = "xrefcheck";
+              contents = [ binOnly pkgs.cacert ];
+              config.Entrypoint = "xrefcheck";
+            };
+          };
+
+          checks = {
+            trailing-whitespace = pkgs.build.checkTrailingWhitespace ./.;
+            reuse-lint = pkgs.build.reuseLint ./.;
+          };
+        }
+      ]
+    );
+}
diff --git a/nix/sources.json b/nix/sources.json
deleted file mode 100644
index 547682a..0000000
--- a/nix/sources.json
+++ /dev/null
@@ -1,74 +0,0 @@
-{
-    "hackage.nix": {
-        "branch": "master",
-        "description": "Automatically generated Nix expressions for Hackage",
-        "homepage": "",
-        "owner": "input-output-hk",
-        "repo": "hackage.nix",
-        "rev": "af1008186119c18e9f4f42e1c463d69d5b5fd288",
-        "sha256": "1569jk15y3xq8wnjnf151xb125r2drr0cpska6mgsbpiddlp0mr6",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/hackage.nix/archive/af1008186119c18e9f4f42e1c463d69d5b5fd288.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "haskell.nix": {
-        "branch": "master",
-        "description": "Alternative Haskell Infrastructure for Nixpkgs",
-        "homepage": "https://input-output-hk.github.io/haskell.nix",
-        "owner": "input-output-hk",
-        "repo": "haskell.nix",
-        "rev": "b302c7a5b5fe1379f57abb81cbf1c0daabe44616",
-        "sha256": "0cqbm6xxkn5dmm21cxcrv7yvz8lz6kssp5cj4bf837kirbbg037j",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/haskell.nix/archive/b302c7a5b5fe1379f57abb81cbf1c0daabe44616.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs": {
-        "branch": "master",
-        "description": "Pinned Nixpkgs tree (master follows nixos-unstable-small, only tags have stable history)",
-        "homepage": "",
-        "owner": "serokell",
-        "repo": "nixpkgs",
-        "rev": "7887e272ab2ad8376d54ca5f58df0ed7f67676e6",
-        "sha256": "0sx7ff2ps79izkaqnigyj85vs6jffvx8x9kgl0qf4wv0n3b2wwmj",
-        "type": "tarball",
-        "url": "https://github.com/serokell/nixpkgs/archive/7887e272ab2ad8376d54ca5f58df0ed7f67676e6.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs-stylish": {
-        "branch": "master",
-        "description": "Nix Packages collection",
-        "homepage": "",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "19574af0af3ffaf7c9e359744ed32556f34536bd",
-        "sha256": "0v3c4r8v40jimicdxqvxnzmdypnafm2baam7z131zk6ljhb8jpg9",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/19574af0af3ffaf7c9e359744ed32556f34536bd.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "serokell.nix": {
-        "branch": "master",
-        "description": "Serokell Nix infrastructure library",
-        "homepage": null,
-        "owner": "serokell",
-        "repo": "serokell.nix",
-        "rev": "652105c5fc5564f5d8e682d61bdc0d51bbc1f939",
-        "sha256": "19zkjhyjbksf2fw32h7m3x0v8nvgdy2qkjkxg2qzzb25as245vmj",
-        "type": "tarball",
-        "url": "https://github.com/serokell/serokell.nix/archive/652105c5fc5564f5d8e682d61bdc0d51bbc1f939.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "stackage.nix": {
-        "branch": "master",
-        "description": "Automatically generated Nix expressions of Stackage snapshots",
-        "homepage": "",
-        "owner": "input-output-hk",
-        "repo": "stackage.nix",
-        "rev": "9ef56f70c138620b65ea42cade5e493418b0ae50",
-        "sha256": "0jrnv0w2yqkxkfnc64y7qrab7grr84mwp56y6r5x1npw174wpl8v",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/stackage.nix/archive/9ef56f70c138620b65ea42cade5e493418b0ae50.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    }
-}
diff --git a/nix/sources.json.license b/nix/sources.json.license
deleted file mode 100644
index fc8438c..0000000
--- a/nix/sources.json.license
+++ /dev/null
@@ -1,2 +0,0 @@
-# SPDX-FileCopyrightText: 2019 Serokell <https://serokell.io>
-# SPDX-License-Identifier: MPL-2.0
diff --git a/nix/sources.nix b/nix/sources.nix
deleted file mode 100644
index 1938409..0000000
--- a/nix/sources.nix
+++ /dev/null
@@ -1,174 +0,0 @@
-# This file has been generated by Niv.
-
-let
-
-  #
-  # The fetchers. fetch_<type> fetches specs of type <type>.
-  #
-
-  fetch_file = pkgs: name: spec:
-    let
-      name' = sanitizeName name + "-src";
-    in
-      if spec.builtin or true then
-        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
-      else
-        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
-
-  fetch_tarball = pkgs: name: spec:
-    let
-      name' = sanitizeName name + "-src";
-    in
-      if spec.builtin or true then
-        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
-      else
-        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
-
-  fetch_git = name: spec:
-    let
-      ref =
-        if spec ? ref then spec.ref else
-          if spec ? branch then "refs/heads/${spec.branch}" else
-            if spec ? tag then "refs/tags/${spec.tag}" else
-              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
-    in
-      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
-
-  fetch_local = spec: spec.path;
-
-  fetch_builtin-tarball = name: throw
-    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
-        $ niv modify ${name} -a type=tarball -a builtin=true'';
-
-  fetch_builtin-url = name: throw
-    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
-        $ niv modify ${name} -a type=file -a builtin=true'';
-
-  #
-  # Various helpers
-  #
-
-  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
-  sanitizeName = name:
-    (
-      concatMapStrings (s: if builtins.isList s then "-" else s)
-        (
-          builtins.split "[^[:alnum:]+._?=-]+"
-            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
-        )
-    );
-
-  # The set of packages used when specs are fetched using non-builtins.
-  mkPkgs = sources: system:
-    let
-      sourcesNixpkgs =
-        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
-      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
-      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
-    in
-      if builtins.hasAttr "nixpkgs" sources
-      then sourcesNixpkgs
-      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
-        import <nixpkgs> {}
-      else
-        abort
-          ''
-            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
-            add a package called "nixpkgs" to your sources.json.
-          '';
-
-  # The actual fetching function.
-  fetch = pkgs: name: spec:
-
-    if ! builtins.hasAttr "type" spec then
-      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
-    else if spec.type == "file" then fetch_file pkgs name spec
-    else if spec.type == "tarball" then fetch_tarball pkgs name spec
-    else if spec.type == "git" then fetch_git name spec
-    else if spec.type == "local" then fetch_local spec
-    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
-    else if spec.type == "builtin-url" then fetch_builtin-url name
-    else
-      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
-
-  # If the environment variable NIV_OVERRIDE_${name} is set, then use
-  # the path directly as opposed to the fetched source.
-  replace = name: drv:
-    let
-      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
-      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
-    in
-      if ersatz == "" then drv else
-        # this turns the string into an actual Nix path (for both absolute and
-        # relative paths)
-        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
-
-  # Ports of functions for older nix versions
-
-  # a Nix version of mapAttrs if the built-in doesn't exist
-  mapAttrs = builtins.mapAttrs or (
-    f: set: with builtins;
-    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
-  );
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
-  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
-  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
-  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
-  concatMapStrings = f: list: concatStrings (map f list);
-  concatStrings = builtins.concatStringsSep "";
-
-  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
-  optionalAttrs = cond: as: if cond then as else {};
-
-  # fetchTarball version that is compatible between all the versions of Nix
-  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchTarball;
-    in
-      if lessThan nixVersion "1.12" then
-        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
-      else
-        fetchTarball attrs;
-
-  # fetchurl version that is compatible between all the versions of Nix
-  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchurl;
-    in
-      if lessThan nixVersion "1.12" then
-        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
-      else
-        fetchurl attrs;
-
-  # Create the final "sources" from the config
-  mkSources = config:
-    mapAttrs (
-      name: spec:
-        if builtins.hasAttr "outPath" spec
-        then abort
-          "The values in sources.json should not have an 'outPath' attribute"
-        else
-          spec // { outPath = replace name (fetch config.pkgs name spec); }
-    ) config.sources;
-
-  # The "config" used by the fetchers
-  mkConfig =
-    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
-    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
-    , system ? builtins.currentSystem
-    , pkgs ? mkPkgs sources system
-    }: rec {
-      # The sources, i.e. the attribute set of spec name to spec
-      inherit sources;
-
-      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
-      inherit pkgs;
-    };
-
-in
-mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }
diff --git a/nix/sources.nix.license b/nix/sources.nix.license
deleted file mode 100644
index cda8f7f..0000000
--- a/nix/sources.nix.license
+++ /dev/null
@@ -1,2 +0,0 @@
-# SPDX-FileCopyrightText: 2019 Nicolas Mattia
-# SPDX-License-Identifier: LicenseRef-MIT-Mattia
diff --git a/xrefcheck.nix b/xrefcheck.nix
deleted file mode 100644
index 057f5ce..0000000
--- a/xrefcheck.nix
+++ /dev/null
@@ -1,47 +0,0 @@
-# SPDX-FileCopyrightText: 2020 Serokell <https://serokell.io>
-#
-# SPDX-License-Identifier: MPL-2.0
-
-{ linux ? false, linux-static ? false, windows ? false }:
-let
-  nixpkgs = (import ./ci.nix).pkgs;
-  src = (import ./ci.nix).project-src;
-  pkgs = if linux-static then nixpkgs.pkgsCross.musl64 else if windows then nixpkgs.pkgsCross.mingwW64 else nixpkgs;
-  project = pkgs.haskell-nix.stackProject {
-    src = pkgs.haskell-nix.haskellLib.cleanGit { src = ./.; keepGitDir = true; };
-    modules = [{
-      packages.xrefcheck = {
-        ghcOptions =
-          [ "-Werror" ];
-
-        components.tests = {
-          ftp-tests = {
-            build-tools = [ pkgs.vsftpd ];
-            preCheck = ''
-              echo "Starting vsftpd..."
-              touch /tmp/vsftpd.log
-              vsftpd \
-              -orun_as_launching_user=yes \
-              -olisten_port=2221 \
-              -olisten=yes \
-              -oftp_username=$(whoami) \
-              -oanon_root=${./ftp-tests/ftp_root} \
-              -opasv_min_port=2222 \
-              -ohide_file='{.*}' \
-              -odeny_file='{.*}' \
-              -oseccomp_sandbox=no \
-              -olog_ftp_protocol=yes \
-              -oxferlog_enable=yes \
-              -ovsftpd_log_file=/tmp/vsftpd.log &
-              sleep 1
-              tail -f /tmp/vsftpd.log &
-            '';
-            testFlags = [ "--ftp-host" "ftp://localhost:2221" ];
-          };
-          xrefcheck-tests.build-tools = [ pkgs.git ];
-        };
-      };
-    }];
-  };
-in
-project.xrefcheck