diff --git a/default.nix b/default.nix
index 16e37dd..39bacff 100644
--- a/default.nix
+++ b/default.nix
@@ -1,27 +1,7 @@
-# SPDX-FileCopyrightText: 2020 Serokell <https://serokell.io/>
-#
-# SPDX-License-Identifier: MPL-2.0
-
-#
-# nix-flakes shim
-#
-
-let
-  sources = builtins.removeAttrs (import ./nix/sources.nix) ["__functor"];
-  # https://github.com/input-output-hk/haskell.nix/blob/master/lib/override-with.nix
-  tryOverride = override: default:
-    let
-      try = builtins.tryEval (builtins.findFile builtins.nixPath override);
-    in if try.success then
-      builtins.trace "using search host <${override}>" try.value
-       else
-         default;
-  inputs = builtins.mapAttrs (name: s: import (tryOverride "flake-${name}" s)) sources;
-  flake = (import ./flake.nix).outputs (inputs // { self = flake; });
-in
-{ exposeFlake ? false }:
-if exposeFlake then
-  flake
-else {
-  inherit (flake.packages) with-utf8;
-}
+(import (
+  fetchTarball {
+    url = "https://github.com/edolstra/flake-compat/archive/99f1c2157fba4bfe6211a321fd0ee43199025dbf.tar.gz";
+    sha256 = "0x2jn3vrawwv9xp15674wjz9pixwjyj3j771izayl962zziivbx2"; }
+) {
+  src =  ./.;
+}).defaultNix
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..dfad10c
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,60 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1610051610,
+        "narHash": "sha256-U9rPz/usA1/Aohhk7Cmc2gBrEEKRzcW4nwPWMPwja4Y=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "3982c9903e93927c2164caa727cd3f6a0e6d14cc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "haskell-nix": {
+      "locked": {
+        "lastModified": 1613524507,
+        "narHash": "sha256-vIjgOb6PKGtLpSDbKV6J2dI4nR8SOcST1I1B+qOhsR8=",
+        "owner": "input-output-hk",
+        "repo": "haskell.nix",
+        "rev": "ba87ffb84bc4158ada14908bddee9df2c81ac31b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "haskell.nix",
+        "rev": "ba87ffb84bc4158ada14908bddee9df2c81ac31b",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1608007629,
+        "narHash": "sha256-lipVFC/a2pzzA5X2ULj64je+fz1JIp2XRrB5qyoizpQ=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "f02bf8ffb9a5ec5e8f6f66f1e5544fd2aa1a0693",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "f02bf8ffb9a5ec5e8f6f66f1e5544fd2aa1a0693",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "haskell-nix": "haskell-nix",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
index 0d9fdd6..48bd7e4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,31 +3,42 @@
 # SPDX-License-Identifier: MPL-2.0
 
 {
-  edition = 201911;
-
   description = "Get your UTF-8 IO right on the first try";
 
-  outputs = { self, nixpkgs, haskell-nix }:
-    let
-      pkgs = nixpkgs {
-        overlays = haskell-nix.overlays;
-      };
+  inputs = {
+    flake-utils.url = "github:numtide/flake-utils";
+    haskell-nix.url = "github:input-output-hk/haskell.nix/ba87ffb84bc4158ada14908bddee9df2c81ac31b";
+    nixpkgs.url = "github:nixos/nixpkgs/f02bf8ffb9a5ec5e8f6f66f1e5544fd2aa1a0693";
+  };
 
-      project = pkgs.haskell-nix.stackProject {
-        src = pkgs.haskell-nix.haskellLib.cleanGit {
-          name = "with-utf8";
-          src = ./.;
+  outputs = { self, nixpkgs, flake-utils, haskell-nix }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system}.extend haskell-nix.overlay;
+
+        project = pkgs.haskell-nix.stackProject {
+          src = pkgs.haskell-nix.haskellLib.cleanGit {
+            name = "with-utf8";
+            src = ./.;
+          };
         };
-      };
-      with-utf8 = project.with-utf8;
-    in {
-      packages = {
-        with-utf8 = with-utf8.components.library;
-      };
+        with-utf8 = project.with-utf8;
+      in rec {
+        packages = {
+          with-utf8 = with-utf8.components.library;
+        };
+        defaultPackage = packages.with-utf8;
 
-      checks = {
-        build = self.packages.with-utf8;
-        test = with-utf8.checks.with-utf8-test;
-      };
-    };
+        checks = {
+          build = packages.with-utf8;
+          test = with-utf8.checks.with-utf8-test;
+        };
+
+        apps.utf8-troubleshoot = {
+          type = "app";
+          program = "${with-utf8.components.exes.utf8-troubleshoot}/bin/utf8-troubleshoot";
+        };
+        defaultApp = apps.utf8-troubleshoot;
+      }
+    );
 }
diff --git a/nix/sources.json b/nix/sources.json
deleted file mode 100644
index 831db56..0000000
--- a/nix/sources.json
+++ /dev/null
@@ -1,26 +0,0 @@
-{
-    "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": "e9f59def792a01b9937ef0c27fe96903aa173829",
-        "sha256": "19384g77wd8rxpryj12m2002l7nfw3j9nv1w44j2apayj9y8sbll",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/haskell.nix/archive/e9f59def792a01b9937ef0c27fe96903aa173829.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": "17d9bc51f6cbc37339332e9bf9e82d172c642e7c",
-        "sha256": "0ckvgiif2xwbrl0sd301p4nldkc3y7qpvrvag9pykswsissbhi5v",
-        "type": "tarball",
-        "url": "https://github.com/serokell/nixpkgs/archive/17d9bc51f6cbc37339332e9bf9e82d172c642e7c.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 0095d07..0000000
--- a/nix/sources.json.license
+++ /dev/null
@@ -1,3 +0,0 @@
-SPDX-FileCopyrightText: 2020 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 2de89a6..0000000
--- a/nix/sources.nix
+++ /dev/null
@@ -1,96 +0,0 @@
-# This file has been generated by Niv.
-
-# A record, from name to path, of the third-party packages
-with rec
-{
-  pkgs =
-    if hasNixpkgsPath
-    then
-      if hasThisAsNixpkgsPath
-      then import (builtins_fetchTarball { inherit (sources_nixpkgs) url sha256; }) {}
-      else import <nixpkgs> {}
-    else
-      import (builtins_fetchTarball { inherit (sources_nixpkgs) url sha256; }) {};
-
-  sources_nixpkgs =
-    if builtins.hasAttr "nixpkgs" sources
-    then sources.nixpkgs
-    else abort
-      ''
-        Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
-        add a package called "nixpkgs" to your sources.json.
-      '';
-
-  # fetchTarball version that is compatible between all the versions of Nix
-  builtins_fetchTarball = { url, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchTarball;
-    in
-      if lessThan nixVersion "1.12" then
-        fetchTarball { inherit url; }
-      else
-        fetchTarball attrs;
-
-  # fetchurl version that is compatible between all the versions of Nix
-  builtins_fetchurl = { url, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchurl;
-    in
-      if lessThan nixVersion "1.12" then
-        fetchurl { inherit url; }
-      else
-        fetchurl attrs;
-
-  # A wrapper around pkgs.fetchzip that has inspectable arguments,
-  # annoyingly this means we have to specify them
-  fetchzip = { url, sha256 }@attrs: pkgs.fetchzip attrs;
-
-  # A wrapper around pkgs.fetchurl that has inspectable arguments,
-  # annoyingly this means we have to specify them
-  fetchurl = { url, sha256 }@attrs: pkgs.fetchurl attrs;
-
-  hasNixpkgsPath = (builtins.tryEval <nixpkgs>).success;
-  hasThisAsNixpkgsPath =
-    (builtins.tryEval <nixpkgs>).success && <nixpkgs> == ./.;
-
-  sources = builtins.fromJSON (builtins.readFile ./sources.json);
-
-  mapAttrs = builtins.mapAttrs or (
-    f: set: with builtins;
-    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
-  );
-
-  # borrowed from nixpkgs
-  functionArgs = f: f.__functionArgs or (builtins.functionArgs f);
-  callFunctionWith = autoArgs: f: args:
-    let
-      auto = builtins.intersectAttrs (functionArgs f) autoArgs;
-    in
-      f (auto // args);
-
-  getFetcher = spec:
-    let
-      fetcherName =
-        if builtins.hasAttr "type" spec
-        then builtins.getAttr "type" spec
-        else "builtin-tarball";
-    in
-      builtins.getAttr fetcherName {
-        "tarball" = fetchzip;
-        "builtin-tarball" = builtins_fetchTarball;
-        "file" = fetchurl;
-        "builtin-url" = builtins_fetchurl;
-      };
-};
-# NOTE: spec must _not_ have an "outPath" attribute
-mapAttrs (
-  _: spec:
-    if builtins.hasAttr "outPath" spec
-    then abort
-      "The values in sources.json should not have an 'outPath' attribute"
-    else
-      if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
-      then
-        spec // { outPath = callFunctionWith spec (getFetcher spec) {}; }
-      else spec
-) sources
diff --git a/nix/sources.nix.license b/nix/sources.nix.license
deleted file mode 100644
index 9505878..0000000
--- a/nix/sources.nix.license
+++ /dev/null
@@ -1,3 +0,0 @@
-SPDX-FileCopyrightText: 2019 Nicolas Mattia
-
-SPDX-License-Identifier: LicenseRef-MIT-nmattia