diff --git a/flake.nix b/flake.nix
index a6ddc26..44a98c3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,7 +5,7 @@
     pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
     flake-utils.url = "github:numtide/flake-utils";
     flake-compat = {
-      url = github:edolstra/flake-compat;
+      url = "github:edolstra/flake-compat";
       flake = false;
     };
   };
@@ -16,8 +16,7 @@
   }:
     flake-utils.lib.eachSystem ["x86_64-linux"] (
       system: let
-        pkgs = inputs.nixpkgs.legacyPackages.${system};
-        inherit (pkgs) lib haskellPackages haskell;
+        inherit (inputs.nixpkgs.legacyPackages.${system}) lib haskellPackages haskell;
         golden-test = import ./test/golden1.nix {
           seed = "1";
           inherit system;
@@ -45,14 +44,17 @@
             ];
             hooks = {
               hlint.enable = true;
-              cabal-fmt.enable = true;
               alejandra.enable = true;
+              nix-linter.enable = true;
+              statix.enable = true;
               fourmolu.enable = true;
+              cabal-fmt.enable = true;
+              shellcheck.enable = true;
             };
           };
         };
         devShell = haskellPackages.shellFor {
-          packages = p: [defaultPackage];
+          packages = _: [defaultPackage];
           buildInputs = [inputs.pre-commit-hooks.defaultPackage.${system}];
           withHoogle = true;
           inherit (self.checks.${system}.pre-commit-check) shellHook;
diff --git a/nix/sources.json b/nix/sources.json
deleted file mode 100644
index cb8dd32..0000000
--- a/nix/sources.json
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-    "nixpkgs": {
-        "branch": "nixos-unstable",
-        "description": "Nix Packages collection",
-        "homepage": "",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "48d63e924a2666baf37f4f14a18f19347fbd54a2",
-        "sha256": "0dcxc4yc2y5z08pmkmjws4ir0r2cbc5mha2a48bn0bk7nxc6wx8g",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/48d63e924a2666baf37f4f14a18f19347fbd54a2.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    }
-}
diff --git a/nix/sources.nix b/nix/sources.nix
deleted file mode 100644
index 5285449..0000000
--- a/nix/sources.nix
+++ /dev/null
@@ -1,226 +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/test/golden2.nix b/test/golden2.nix
index 598cdab..51c5673 100644
--- a/test/golden2.nix
+++ b/test/golden2.nix
@@ -26,6 +26,7 @@ with import <nixpkgs> {}; let
   build2 = pkgs.runCommand "build2" {} ''
     sleep 3s
     cat ${build5}
+    cat ${build6}
     cat ${build1}
     echo "test" > $out
   '';