diff --git a/build.nix b/build.nix
index 3e232af8..9b349714 100644
--- a/build.nix
+++ b/build.nix
@@ -35,7 +35,7 @@ in rec {
   maintainer-scripts = pkgs.dontRecurseIntoAttrs {
     update-hackage = import ./scripts/update-hackage.nix {
       inherit (pkgs) stdenv lib writeScript coreutils glibc git
-        openssh nix-prefetch-git gawk bash curl findutils;
+        openssh nixFlakes gawk bash curl findutils;
       # Update scripts use the internal nix-tools and cabal-install (compiled with a fixed GHC version)
       nix-tools = haskell.internal-nix-tools;
       cabal-install = haskell.internal-cabal-install;
@@ -43,7 +43,7 @@ in rec {
     };
     update-stackage = haskell.callPackage ./scripts/update-stackage.nix {
       inherit (pkgs) stdenv lib writeScript coreutils glibc git
-        openssh nix-prefetch-git gawk bash curl findutils;
+        openssh nixFlakes gawk bash curl findutils;
       # Update scripts use the internal nix-tools and cabal-install (compiled with a fixed GHC version)
       nix-tools = haskell.internal-nix-tools;
       cabal-install = haskell.internal-cabal-install;
diff --git a/changelog.md b/changelog.md
index 0154cf5c..5e8fcaf9 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,6 +1,12 @@
 This file contains a summary of changes to Haskell.nix and `nix-tools`
 that will impact users.
 
+## Aug 6, 2021
+* Included dependencies of haskell.nix that were tracked in `nix/sources.json`
+  as flake inputs (`flake.lock` replaces `nix/sources.json`).
+* Uses `flake-compat` to continue to provide a compatible interface for non
+  flake projects.
+
 ## Jul 23, 2021
 * `source-repository-package` references in `cabal.project` files are now
   left as a `source-repository-package` when calculating the the `plan-nix` for
diff --git a/ci-lib.nix b/ci-lib.nix
index 4aa541cd..23839cf9 100644
--- a/ci-lib.nix
+++ b/ci-lib.nix
@@ -1,8 +1,8 @@
-let
+{
   # Generic nixpkgs, use *only* for lib functions that are stable across versions
-  pkgs = import (import ./nix/sources.nix).nixpkgs {};
-  lib = pkgs.lib;
-in rec {
+  pkgs ? (import ./. {}).pkgs,
+  lib ? pkgs.lib
+}: rec {
   inherit (import ./dimension.nix) dimension;
 
   # A filter for removing packages that aren't supported on the current platform
diff --git a/ci.nix b/ci.nix
index ffd94483..8a93c14c 100644
--- a/ci.nix
+++ b/ci.nix
@@ -4,10 +4,11 @@
 , ifdLevel ? 3
 # Whether or not we are evaluating in restricted mode. This is true in Hydra, but not in Hercules.
 , restrictEval ? false
-, checkMaterialization ? false }:
+, checkMaterialization ? false
+, pkgs ? (import ./. {}).pkgs }:
  let
-  inherit (import ./ci-lib.nix) dimension platformFilterGeneric filterAttrsOnlyRecursive;
-  sources = import ./nix/sources.nix {};
+  inherit (import ./ci-lib.nix { inherit pkgs; }) dimension platformFilterGeneric filterAttrsOnlyRecursive;
+  inherit (pkgs.haskell-nix) sources;
   nixpkgsVersions = {
     "R2009" = "nixpkgs-2009";
     "R2105" = "nixpkgs-2105";
diff --git a/default.nix b/default.nix
index 4702756d..0de8f155 100644
--- a/default.nix
+++ b/default.nix
@@ -1,23 +1,17 @@
-{ checkMaterialization ? false  # Allows us to easily switch on materialization checking
-, system ? builtins.currentSystem
-, sourcesOverride ? {}
-, ... }@args: rec {
-  sources  = (import ./nix/sources.nix { inherit pkgs; }) // sourcesOverride;
-  config   = import ./config.nix;
-  overlays = [ allOverlays.combined ] ++ (
-    if checkMaterialization == true
-      then [(
-        final: prev: {
-          haskell-nix = prev.haskell-nix // {
-            checkMaterialization = true;
-          };
-        }
-      )]
-      else []
-  );
-  allOverlays = import ./overlays args;
-  nixpkgsArgs = { inherit config overlays system; };
-  pkgs = import sources.nixpkgs nixpkgsArgs;
-  pkgs-unstable = import sources.nixpkgs-unstable nixpkgsArgs;
-  hix = import ./hix/default.nix;
-}
+{...}@args:
+
+let
+  nixpkgsSrc = 
+    builtins.fetchTarball {
+      url = "https://github.com/NixOS/nixpkgs/archive/3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8.tar.gz";
+      sha256 = "sha256:0jf9l6j60sa8cms7r4a02kr9j9884pwv1prf79b2ysnxmnhimnch";
+    };
+  pkgs = args.pkgs or import nixpkgsSrc {};
+  flake-compat =
+    pkgs.fetchzip {
+      url = "https://github.com/hamishmack/flake-compat/archive/ce16b21b8a5588aa8b532353d3ceea89a38b8e77.tar.gz";
+      sha256 = "sha256:054nsfqh3wy6v6bjamw0k91xl8v1rc5x2laic8mphrkrhzvyz5hi";
+    };
+  self = import flake-compat { src = ./.; inherit pkgs; };
+in self.defaultNix.internal.compat
+({ system = args.pkgs.system or builtins.currentSystem; } // args) // self.defaultNix
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 00000000..d4260764
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,285 @@
+{
+  "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"
+      }
+    },
+    "cabal-32": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1603716527,
+        "narHash": "sha256-sDbrmur9Zfp4mPKohCD8IDZfXJ0Tjxpmr2R+kg5PpSY=",
+        "owner": "haskell",
+        "repo": "cabal",
+        "rev": "94aaa8e4720081f9c75497e2735b90f6a819b08e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "3.2",
+        "repo": "cabal",
+        "type": "github"
+      }
+    },
+    "cabal-34": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1622475795,
+        "narHash": "sha256-chwTL304Cav+7p38d9mcb+egABWmxo2Aq+xgVBgEb/U=",
+        "owner": "haskell",
+        "repo": "cabal",
+        "rev": "b086c1995cdd616fc8d91f46a21e905cc50a1049",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "3.4",
+        "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"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1623875721,
+        "narHash": "sha256-A8BU7bjS5GirpAUv4QA+QnJ4CceLHkcXdRp4xITDB0s=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "f7e004a55b120c02ecb6219596820fcd32ca8772",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "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"
+      }
+    },
+    "hackage": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1628212308,
+        "narHash": "sha256-UcqeNBgYDRjWN1+VRRKbviPYCRFocamjOe5xTgyqo14=",
+        "owner": "input-output-hk",
+        "repo": "hackage.nix",
+        "rev": "9bdefa51c864bbef48a2758b05b4b568f0ded62b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "hackage.nix",
+        "type": "github"
+      }
+    },
+    "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"
+      }
+    },
+    "nix-tools": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1626997434,
+        "narHash": "sha256-1judQmP298ao6cGUNxcGhcAXHOnA9qSLvWk/ZtoUL7w=",
+        "owner": "input-output-hk",
+        "repo": "nix-tools",
+        "rev": "c8c5e6a6fbb12a73598d1a434984a36e880ce3cf",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "nix-tools",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1624291665,
+        "narHash": "sha256-kNkaoa3dai9WOi7fsPklCCWZ8hRAkXx0ZUhpYKShyUk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-20.09-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "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-2009": {
+      "locked": {
+        "lastModified": 1624271064,
+        "narHash": "sha256-qns/uRW7MR2EfVf6VEeLgCsCp7pIOjDeR44JzTF09MA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "46d1c3f28ca991601a53e9a14fdd53fcd3dd8416",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-20.09-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-2105": {
+      "locked": {
+        "lastModified": 1624291665,
+        "narHash": "sha256-kNkaoa3dai9WOi7fsPklCCWZ8hRAkXx0ZUhpYKShyUk=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-21.05-darwin",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1623862044,
+        "narHash": "sha256-mY7nldu9Wl/Yb0qMPihZrWw0bRWXNsk6iyYztw/6F6Y=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0747387223edf1aa5beaedf48983471315d95e16",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "old-ghc-nix": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1621819714,
+        "narHash": "sha256-EJCnYQSWk7FRLwS0lZgTWIiQ6pcvDX1VuD6LGD4Uwzs=",
+        "owner": "angerman",
+        "repo": "old-ghc-nix",
+        "rev": "f089a6f090cdb35fcf95f865fc6a31ba6b3ac4eb",
+        "type": "github"
+      },
+      "original": {
+        "owner": "angerman",
+        "ref": "master2",
+        "repo": "old-ghc-nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "HTTP": "HTTP",
+        "cabal-32": "cabal-32",
+        "cabal-34": "cabal-34",
+        "cardano-shell": "cardano-shell",
+        "flake-utils": "flake-utils",
+        "ghc-8.6.5-iohk": "ghc-8.6.5-iohk",
+        "hackage": "hackage",
+        "hpc-coveralls": "hpc-coveralls",
+        "nix-tools": "nix-tools",
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-2003": "nixpkgs-2003",
+        "nixpkgs-2009": "nixpkgs-2009",
+        "nixpkgs-2105": "nixpkgs-2105",
+        "nixpkgs-unstable": "nixpkgs-unstable",
+        "old-ghc-nix": "old-ghc-nix",
+        "stackage": "stackage"
+      }
+    },
+    "stackage": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1628125397,
+        "narHash": "sha256-XXJwp4LJHZhCtGTIrZWV1mCz/0FtZEqxh9Z1k+9msWI=",
+        "owner": "input-output-hk",
+        "repo": "stackage.nix",
+        "rev": "452e9c671ca172a355dbd2582bdb50ef5133af26",
+        "type": "github"
+      },
+      "original": {
+        "owner": "input-output-hk",
+        "repo": "stackage.nix",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
index 419d3ba0..c418a8ee 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,36 +2,125 @@
   description = "Alternative Haskell Infrastructure for Nixpkgs";
 
   inputs = {
-    # Note: keep this in sync with sources.json!
-    nixpkgs.url = github:NixOS/nixpkgs/3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8;
-    nixpkgs-2009.url = github:NixOS/nixpkgs/46d1c3f28ca991601a53e9a14fdd53fcd3dd8416;
-    nixpkgs-2105.url = github:NixOS/nixpkgs/3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8;
-    nixpkgs-unstable.url = github:NixOS/nixpkgs/0747387223edf1aa5beaedf48983471315d95e16;
-  };
-
-  outputs = { self, nixpkgs, ... }:
-  {
-
-    internal = rec {
-      config = import ./config.nix;
-
-      nixpkgsArgs = {
-        inherit config;
-        overlays = [ self.overlay ];
-      };
+    nixpkgs = { url = "github:NixOS/nixpkgs/nixpkgs-20.09-darwin"; };
+    nixpkgs-2003 = { url = "github:NixOS/nixpkgs/nixpkgs-20.03-darwin"; };
+    nixpkgs-2009 = { url = "github:NixOS/nixpkgs/nixpkgs-20.09-darwin"; };
+    nixpkgs-2105 = { url = "github:NixOS/nixpkgs/nixpkgs-21.05-darwin"; };
+    nixpkgs-unstable = { url = "github:NixOS/nixpkgs/nixpkgs-unstable"; };
+    flake-utils = { url = "github:numtide/flake-utils"; };
+    hackage = {
+      url = "github:input-output-hk/hackage.nix";
+      flake = false;
+    };
+    stackage = {
+      url = "github:input-output-hk/stackage.nix";
+      flake = false;
+    };
+    cabal-32 = {
+      url = "github:haskell/cabal/3.2";
+      flake = false;
+    };
+    cabal-34 = {
+      url = "github:haskell/cabal/3.4";
+      flake = false;
+    };
+    cardano-shell = {
+      url = "github:input-output-hk/cardano-shell";
+      flake = false;
+    };
+    "ghc-8.6.5-iohk" = {
+      type = "github";
+      owner = "input-output-hk";
+      repo = "ghc";
+      ref = "release/8.6.5-iohk";
+      flake = false;
+    };
+    hpc-coveralls = {
+      url = "github:sevanspowell/hpc-coveralls";
+      flake = false;
+    };
+    nix-tools = {
+      url = "github:input-output-hk/nix-tools";
+      flake = false;
+    };
+    old-ghc-nix = {
+      url = "github:angerman/old-ghc-nix/master2";
+      flake = false;
+    };
+    HTTP = {
+      url = "github:phadej/HTTP";
+      flake = false;
     };
-
-    overlay = self.overlays.combined;
-    overlays = import ./overlays {};
-
-    legacyPackages = let
-      genAttrs = lst: f:
-        builtins.listToAttrs (map (name: {
-          inherit name;
-          value = f name;
-        }) lst);
-    in genAttrs [ "x86_64-linux" "x86_64-darwin" ] (system:
-      import nixpkgs
-      (self.internal.nixpkgsArgs // { localSystem = { inherit system; }; }));
   };
+
+  outputs = { self, nixpkgs, nixpkgs-unstable, flake-utils, ... }@inputs:
+    let compiler = "ghc884";
+    in {
+      overlay = self.overlays.combined;
+      overlays = import ./overlays { sources = inputs; };
+      internal = rec {
+        config = import ./config.nix;
+        nixpkgsArgs = {
+          inherit config;
+          overlays = [ self.overlay ];
+        };
+      
+        sources = inputs;
+
+        overlaysOverrideable = import ./overlays;
+        # Compatibility with old default.nix
+        compat = { checkMaterialization ?
+            false # Allows us to easily switch on materialization checking
+          , system, sourcesOverride ? { }, ... }@args: rec {
+            sources = inputs // sourcesOverride;
+            allOverlays = import ./overlays args;
+            inherit config nixpkgsArgs;
+            overlays = [ allOverlays.combined ]
+              ++ (if checkMaterialization == true then
+                [
+                  (final: prev: {
+                    haskell-nix = prev.haskell-nix // {
+                      checkMaterialization = true;
+                    };
+                  })
+                ]
+              else
+                [ ]);
+            pkgs = import nixpkgs
+              (nixpkgsArgs // { localSystem = { inherit system; }; });
+            pkgs-unstable = import nixpkgs-unstable
+              (nixpkgsArgs // { localSystem = { inherit system; }; });
+            hix = import ./hix/default.nix { inherit pkgs; };
+          };
+      };
+
+      # Note: `nix flake check` evaluates outputs for all platforms, and haskell.nix
+      # uses IFD heavily, you have to have the ability to build for all platforms
+      # supported by haskell.nix, e.g. with remote builders, in order to check this flake.
+      # If you want to run the tests for just your platform, run `./test/tests.sh` or
+      # `nix-build -A checks.$PLATFORM`
+    } // flake-utils.lib.eachSystem [ "x86_64-linux" "x86_64-darwin" ] (system: {
+      legacyPackages = (self.internal.compat { inherit system; }).pkgs;
+
+      # FIXME: Currently `nix flake check` requires `--impure` because coverage-golden
+      # (and maybe other tests) import projects that use builtins.currentSystem
+      checks = builtins.listToAttrs (map (pkg: {
+        name = pkg.name;
+        value = pkg;
+      }) (nixpkgs.lib.collect nixpkgs.lib.isDerivation (import ./test rec {
+        haskellNix = self.internal.compat { inherit system; };
+        compiler-nix-name = compiler;
+        pkgs = haskellNix.pkgs;
+      })));
+
+      devShell = with self.legacyPackages.${system};
+        mkShell {
+          buildInputs = [
+            nixUnstable
+            cabal-install
+            haskell-nix.compiler.${compiler}
+            haskell-nix.nix-tools.${compiler}
+          ];
+        };
+    });
 }
diff --git a/hix/default.nix b/hix/default.nix
index 55ce6dd5..31cf531b 100644
--- a/hix/default.nix
+++ b/hix/default.nix
@@ -1,26 +1,25 @@
+{ pkgs }:
 let
-  sources = import (../nix/sources.nix) {};
-  nixpkgs = import sources.nixpkgs-2009 {};
   args = '' --arg userDefaults "$HOME/.config/hix/hix.conf" --arg src ./.'';
   # Use HIX_ROOT to override the version of hix used when developing new hix features.
   # See docs/dev/hix.md for details.
   hixProject = "\${HIX_ROOT:-${./..}}/hix/project.nix";
-in nixpkgs.symlinkJoin {
+in pkgs.symlinkJoin {
   name = "hix";
   paths = [
-    (nixpkgs.writeScriptBin "hix-shell" ''
+    (pkgs.writeScriptBin "hix-shell" ''
       nix-shell ${hixProject} ${args} -A shell "$@"
     '')
-    (nixpkgs.writeScriptBin "hix-build" ''
+    (pkgs.writeScriptBin "hix-build" ''
       nix-build ${hixProject} ${args} "$@"
     '')
-    (nixpkgs.writeScriptBin "hix-instantiate" ''
+    (pkgs.writeScriptBin "hix-instantiate" ''
       nix-instantiate ${hixProject} ${args} "$@"
     '')
-    (nixpkgs.writeScriptBin "hix-env" ''
+    (pkgs.writeScriptBin "hix-env" ''
       nix-env -f ${hixProject} ${args} "$@"
     '')
-    (nixpkgs.writeScriptBin "hix" ''
+    (pkgs.writeScriptBin "hix" ''
       cmd=$1
       shift
       case $cmd in
@@ -41,4 +40,4 @@ in nixpkgs.symlinkJoin {
   ];
 } // {
   project = import ./project.nix; 
-}
\ No newline at end of file
+}
diff --git a/hix/project.nix b/hix/project.nix
index 74d478b6..6dc3db03 100644
--- a/hix/project.nix
+++ b/hix/project.nix
@@ -20,7 +20,7 @@ let
       { _module.args.pkgs = {}; }
     ];
   }).config) name;
-  sources = import ../nix/sources.nix {};
+  inherit (import ./.. {}) sources;
   lib = import (sources.nixpkgs-unstable + "/lib");
   commandArgs' =
     builtins.listToAttrs (
diff --git a/lib/default.nix b/lib/default.nix
index 4b9e6681..65a94a7c 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -198,7 +198,7 @@ in {
   cleanGit = import ./clean-git.nix {
     inherit lib cleanSourceWith;
     git = gitMinimal;
-    inherit (pkgs) runCommand;
+    inherit (pkgs.evalPackages.buildPackages) runCommand;
   };
 
   # Some times it is handy to temporarily use a relative path between git
diff --git a/nix/sources.json b/nix/sources.json
deleted file mode 100644
index af982755..00000000
--- a/nix/sources.json
+++ /dev/null
@@ -1,171 +0,0 @@
-{
-    "cabal-32": {
-        "branch": "3.2",
-        "builtin": false,
-        "description": "Official upstream development repository for Cabal and cabal-install",
-        "homepage": "https://haskell.org/cabal",
-        "owner": "haskell",
-        "repo": "cabal",
-        "rev": "94aaa8e4720081f9c75497e2735b90f6a819b08e",
-        "sha256": "09m59w794zk4mxk1m3qkkmf5ydi0zhh89a7jk1wglrgxxadfndmh",
-        "type": "tarball",
-        "url": "https://github.com/haskell/cabal/archive/94aaa8e4720081f9c75497e2735b90f6a819b08e.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "cabal-34": {
-        "branch": "3.4",
-        "description": "Official upstream development repository for Cabal and cabal-install",
-        "homepage": "https://haskell.org/cabal",
-        "owner": "haskell",
-        "repo": "cabal",
-        "rev": "f39af1b67a65dc1bb1fe70e4f02a3e6635f5ee26",
-        "sha256": "06c7q1y1ggbgczg7f4s5zds16n8bkfkdzg7mr5sw9m6gzbhgcby8",
-        "type": "tarball",
-        "url": "https://github.com/haskell/cabal/archive/f39af1b67a65dc1bb1fe70e4f02a3e6635f5ee26.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "cardano-shell": {
-        "branch": "master",
-        "builtin": false,
-        "description": "Node shell, a thin layer for running the node and it's modules.",
-        "homepage": null,
-        "owner": "input-output-hk",
-        "repo": "cardano-shell",
-        "rev": "9392c75087cb9a3d453998f4230930dea3a95725",
-        "sha256": "0gk1i8nkyp7c4jis2phcsr83dnd6g3nds8hpkjah4cp2cza5is9y",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/cardano-shell/archive/9392c75087cb9a3d453998f4230930dea3a95725.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "ghc-8.6.5-iohk": {
-        "branch": "release/8.6.5-iohk",
-        "deepClone": true,
-        "description": "IOHK's ghc fork. See release/X.Y.Z-iohk branches.",
-        "homepage": "",
-        "owner": "input-output-hk",
-        "ref": "release/8.6.5-iohk",
-        "repo": "https://github.com/input-output-hk/ghc.git",
-        "rev": "95713a6ecce4551240da7c96b6176f980af75cae",
-        "sha256": "0hma1zsijw9z2i622qnxpmhahbjdjgq68hz1l57bbm3v9nzh21bc",
-        "type": "git",
-        "url": "https://github.com/input-output-hk/ghc.git",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "hpc-coveralls": {
-        "branch": "master",
-        "builtin": false,
-        "description": "coveralls.io support for haskell code coverage with hpc",
-        "homepage": "http://hackage.haskell.org/package/hpc-coveralls",
-        "owner": "sevanspowell",
-        "repo": "hpc-coveralls",
-        "rev": "14df0f7d229f4cd2e79f8eabb1a740097fdfa430",
-        "sha256": "02dmcmqc845s7sdgdnk3xxn7l6jj8faa7547b4cii9mgv09arspj",
-        "type": "tarball",
-        "url": "https://github.com/sevanspowell/hpc-coveralls/archive/14df0f7d229f4cd2e79f8eabb1a740097fdfa430.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "niv": {
-        "branch": "master",
-        "builtin": false,
-        "description": "Easy dependency management for Nix projects",
-        "homepage": "https://github.com/nmattia/niv",
-        "owner": "nmattia",
-        "repo": "niv",
-        "rev": "f73bf8d584148677b01859677a63191c31911eae",
-        "sha256": "0jlmrx633jvqrqlyhlzpvdrnim128gc81q5psz2lpp2af8p8q9qs",
-        "type": "tarball",
-        "url": "https://github.com/nmattia/niv/archive/f73bf8d584148677b01859677a63191c31911eae.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nix-tools": {
-        "branch": "master",
-        "builtin": false,
-        "description": "Translate Cabals Generic Package Description to a Nix expression",
-        "homepage": null,
-        "owner": "input-output-hk",
-        "repo": "nix-tools",
-        "rev": "15d2e4b61cb63ff351f3c490c12c4d89eafd31a1",
-        "sha256": "15p38dhbhk2c0bq8g9jr0gy01livigz0ca34c2mrwipbd4mipqgm",
-        "type": "tarball",
-        "url": "https://github.com/input-output-hk/nix-tools/archive/15d2e4b61cb63ff351f3c490c12c4d89eafd31a1.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs": {
-        "branch": "nixpkgs-21.05-darwin",
-        "builtin": true,
-        "description": "Nix Packages collection",
-        "homepage": null,
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8",
-        "sha256": "0jf9l6j60sa8cms7r4a02kr9j9884pwv1prf79b2ysnxmnhimnch",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs-2003": {
-        "branch": "nixpkgs-20.03-darwin",
-        "builtin": false,
-        "description": "Nix Packages collection",
-        "homepage": null,
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "1db42b7fe3878f3f5f7a4f2dc210772fd080e205",
-        "sha256": "05k9y9ki6jhaqdhycnidnk5zrdzsdammbk5lsmsbz249hjhhgcgh",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/1db42b7fe3878f3f5f7a4f2dc210772fd080e205.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs-2009": {
-        "branch": "nixpkgs-20.09-darwin",
-        "builtin": false,
-        "description": "Nix Packages collection",
-        "homepage": null,
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "46d1c3f28ca991601a53e9a14fdd53fcd3dd8416",
-        "sha256": "1h7lfhqws2cf8zg30fj8pakh4aw0id3m9yjpgn21scdv2nwkyyxa",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/46d1c3f28ca991601a53e9a14fdd53fcd3dd8416.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs-2105": {
-        "branch": "nixpkgs-21.05-darwin",
-        "builtin": false,
-        "description": "Nix Packages collection",
-        "homepage": null,
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8",
-        "sha256": "0jf9l6j60sa8cms7r4a02kr9j9884pwv1prf79b2ysnxmnhimnch",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/3c6f3f84af60a8ed5b8a79cf3026b7630fcdefb8.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs-unstable": {
-        "branch": "nixpkgs-unstable",
-        "builtin": false,
-        "description": "Nix Packages collection",
-        "homepage": "",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "0747387223edf1aa5beaedf48983471315d95e16",
-        "sha256": "19hpz87vfcr6icxcjdlp2mnk8v5db4l3x32adzc5ynmxvfayg3lr",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/0747387223edf1aa5beaedf48983471315d95e16.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "old-ghc-nix": {
-        "branch": "master2",
-        "builtin": false,
-        "description": "Old and New GHC",
-        "homepage": null,
-        "owner": "angerman",
-        "repo": "old-ghc-nix",
-        "rev": "f089a6f090cdb35fcf95f865fc6a31ba6b3ac4eb",
-        "sha256": "0fy32hz1i2ryp1aps39gjzm9122q2fc9bd045x8v34wn0ihsg40h",
-        "type": "tarball",
-        "url": "https://github.com/angerman/old-ghc-nix/archive/f089a6f090cdb35fcf95f865fc6a31ba6b3ac4eb.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 1938409d..00000000
--- 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/overlays/default.nix b/overlays/default.nix
index 4a541eaa..f001b842 100644
--- a/overlays/default.nix
+++ b/overlays/default.nix
@@ -1,4 +1,4 @@
-args:
+{ sources, ...}@args:
 
 let
   overlays = {
diff --git a/overlays/haskell.nix b/overlays/haskell.nix
index 4f3247b1..692b0117 100644
--- a/overlays/haskell.nix
+++ b/overlays/haskell.nix
@@ -1,5 +1,4 @@
-{ sourcesOverride ? {}
-,  ... }:
+{ sources,  ... }:
 # The haskell.nix infrastructure
 #
 # for hygienic reasons we'll use haskell-nix as a prefix.
@@ -12,25 +11,10 @@ final: prev: {
         # overlays.
         defaultModules = [];
 
-        # Niv based source pins.  See https://github.com/nmattia/niv#niv
-        # for details on how to update this using the niv tool
-        # or edit nix/sources.json manually if you prefer.
-        sources = {
-          # Hackage and stackage still updated by scripts
-          # that predate our use of niv.  We have moved them
-          # here though so that you can still use the
-          # sourcesOverride arg or `niv add` to replace them.
-          hackage = fetchExternal {
-            name     = "hackage-exprs-source";
-            specJSON = hackageSourceJSON;
-            override = "hackage";
-          };
-          stackage = fetchExternal {
-            name     = "stackage-snapshot-source";
-            specJSON = stackageSourceJSON;
-            override = "stackage";
-          };
-        } // (import ../nix/sources.nix { pkgs = final; }) // sourcesOverride;
+        # Nix Flake based source pins.
+        # To update all inputs, get unstable Nix and then `nix flake update --recreate-lock-file`
+        # Or `nix-shell -p nixUnstable --run "nix --experimental-features 'nix-command flakes' flake update --recreate-lock-file"`
+        sources = sources;
 
         # We provide a `callPackage` function to consumers for
         # convenience.  We will however refrain from using it
diff --git a/release.nix b/release.nix
index 8f05fc06..d9681546 100644
--- a/release.nix
+++ b/release.nix
@@ -11,8 +11,8 @@ let
         then __trace (prefix + n) v
         else traceNames (prefix + n + ".") v
       else v);
-  inherit (import ./ci-lib.nix) stripAttrsForHydra filterDerivations;
-  genericPkgs = import (import ./nix/sources.nix).nixpkgs {};
+  inherit (import ./ci-lib.nix { pkgs = genericPkgs; }) stripAttrsForHydra filterDerivations;
+  genericPkgs = (import ./. {}).pkgs;
   lib = genericPkgs.lib;
   ci = import ./ci.nix { inherit supportedSystems ifdLevel checkMaterialization; restrictEval = true; };
   allJobs = stripAttrsForHydra (filterDerivations ci);
diff --git a/scripts/check-hydra.nix b/scripts/check-hydra.nix
index 5d43ba7d..5db09c8c 100644
--- a/scripts/check-hydra.nix
+++ b/scripts/check-hydra.nix
@@ -1,4 +1,4 @@
-{ stdenv, lib, writeScript, coreutils, time, gnutar, gzip, hydra-migration, jq }:
+{ stdenv, lib, writeScript, coreutils, time, gnutar, gzip, hydra-migration, jq, gitMinimal }:
 
 with lib;
 
@@ -7,7 +7,7 @@ writeScript "check-hydra.sh" ''
 
   set -euo pipefail
 
-  export PATH="${makeBinPath [ coreutils time gnutar gzip hydra-migration jq ]}"
+  export PATH="${makeBinPath [ coreutils time gnutar gzip hydra-migration jq gitMinimal ]}"
 
   echo '~~~ Evaluating release.nix with --arg ifdLevel '$1
   command time --format '%e' -o eval-time.txt \
diff --git a/scripts/check-path-support.nix b/scripts/check-path-support.nix
index c38833d8..44cb8721 100644
--- a/scripts/check-path-support.nix
+++ b/scripts/check-path-support.nix
@@ -1,4 +1,4 @@
-{ stdenv, lib, writeScript, coreutils, gnutar, gzip, nix }:
+{ stdenv, lib, writeScript, coreutils, gnutar, gzip, nix, gitMinimal }:
 
 with lib;
 
@@ -7,7 +7,7 @@ writeScript "check-path-supprot.sh" ''
 
   set -euo pipefail
 
-  export PATH="${makeBinPath [ coreutils gnutar gzip nix ]}"
+  export PATH="${makeBinPath [ coreutils gnutar gzip nix gitMinimal ]}"
 
   nix-build -E '((import ./. {}).pkgs.haskell-nix.cabalProject { compiler-nix-name = "ghc865"; src = ./test/cabal-simple; }).cabal-simple.components.library'
 ''
diff --git a/scripts/update-external.nix b/scripts/update-external.nix
index c47d10e8..88530c87 100644
--- a/scripts/update-external.nix
+++ b/scripts/update-external.nix
@@ -1,5 +1,5 @@
 { stdenv, lib, writeScript, glibc, coreutils, git, openssh
-, nix-tools, cabal-install, nix-prefetch-git
+, nix-tools, cabal-install, nixFlakes
 , bash, curl, findutils, gawk }:
 
 { name, script }:
@@ -16,7 +16,7 @@ in
 
     set -euo pipefail
 
-    export PATH="${makeBinPath ([ coreutils curl findutils gawk bash git openssh nix-tools cabal-install nix-prefetch-git ] ++ optional stdenv.isLinux glibc)}"
+    export PATH="${makeBinPath ([ coreutils curl findutils gawk bash git openssh nix-tools cabal-install nixFlakes ] ++ optional stdenv.isLinux glibc)}"
 
     ${script}
 
@@ -35,5 +35,5 @@ in
 
     cd ..
 
-    nix-prefetch-git ${repoHTTPS} --rev "$rev" | tee ${name}-src.json
+    nix --experimental-features 'nix-command flakes' flake lock --update-input ${name}
   ''
diff --git a/scripts/update-hackage.nix b/scripts/update-hackage.nix
index 78c6d891..e0ef77d5 100644
--- a/scripts/update-hackage.nix
+++ b/scripts/update-hackage.nix
@@ -1,5 +1,5 @@
 { stdenv, lib, writeScript, coreutils, glibc, git, openssh
-, nix-tools, cabal-install, nix-prefetch-git
+, nix-tools, cabal-install, nixFlakes
 , gawk, bash, curl, findutils
 , update-index-state-hashes }@args:
 
diff --git a/scripts/update-stackage.nix b/scripts/update-stackage.nix
index 0cfa9989..5227b469 100644
--- a/scripts/update-stackage.nix
+++ b/scripts/update-stackage.nix
@@ -1,5 +1,5 @@
 { stdenv, lib, writeScript, coreutils, glibc, git, openssh
-, nix-tools, cabal-install, nix-prefetch-git
+, nix-tools, cabal-install, nixFlakes
 , gawk, bash, curl, findutils }@args:
 
 import ./update-external.nix args {
diff --git a/shell.nix b/shell.nix
index eb7532ef..c22e7e63 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,12 +1 @@
-let
-  inherit (import ./default.nix {}) sources nixpkgsArgs;
-  pkgs = import sources.nixpkgs nixpkgsArgs;
-in pkgs.stdenv.mkDerivation rec {
-  name = "env";
-  env = pkgs.buildEnv { name = name; paths = buildInputs; };
-  buildInputs = [
-    pkgs.cabal-install
-    pkgs.haskell-nix.ghc
-    pkgs.haskell-nix.nix-tools
-  ];
-}
+(import ./default.nix {}).devShell.${builtins.currentSystem}
diff --git a/test/default.nix b/test/default.nix
index 90eab689..7a70cb2f 100644
--- a/test/default.nix
+++ b/test/default.nix
@@ -1,4 +1,4 @@
-{ haskellNix ? import ../default.nix { inherit checkMaterialization; }
+{ haskellNix ? import ../default.nix { }
 , pkgs ? import nixpkgs nixpkgsArgs
 , nixpkgs ? haskellNix.sources.nixpkgs-unstable
 , nixpkgsArgs ? haskellNix.nixpkgsArgs
@@ -10,7 +10,7 @@
 with pkgs;
 
 let
-  inherit (import ../ci-lib.nix) dimension platformFilterGeneric filterAttrsOnlyRecursive;
+  inherit (import ../ci-lib.nix { inherit pkgs; }) dimension platformFilterGeneric filterAttrsOnlyRecursive;
   isDisabled = d: d.meta.disabled or false;
 
   # Set recurseForDerivations for both children and grand-children values in
diff --git a/test/fully-static/cross.nix b/test/fully-static/cross.nix
index fe25d12e..f1ae73a5 100644
--- a/test/fully-static/cross.nix
+++ b/test/fully-static/cross.nix
@@ -1,5 +1,5 @@
 { pkgs ? import nixpkgs { }
-, nixpkgs ? import (../../nix/sources.nix).nixpkgs
+, nixpkgs ? (import ../.. { }).sources.nixpkgs
 }:
 
 let