diff --git a/dhall-nix/formatting.nix b/dhall-nix/formatting.nix
deleted file mode 100644
index cb124ce..0000000
--- a/dhall-nix/formatting.nix
+++ /dev/null
@@ -1,16 +0,0 @@
-{ mkDerivation, array, base, bytestring, clock, ghc-prim, hspec
-, integer-gmp, old-locale, scientific, stdenv, text, time
-, transformers
-}:
-mkDerivation {
-  pname = "formatting";
-  version = "6.3.1";
-  sha256 = "56303c8dff977ef9eb66b67fc30eb079f867201558f5fe6b442ffa06561fd479";
-  libraryHaskellDepends = [
-    array base bytestring clock ghc-prim integer-gmp old-locale
-    scientific text time transformers
-  ];
-  testHaskellDepends = [ base hspec ];
-  description = "Combinator-based type-safe formatting (like printf() or FORMAT)";
-  license = stdenv.lib.licenses.bsd3;
-}
diff --git a/dhall-nix/default.nix b/dhall-nix/nix/dhall-nix.nix
similarity index 97%
rename from dhall-nix/default.nix
rename to dhall-nix/nix/dhall-nix.nix
index 8998d32..366585e 100644
--- a/dhall-nix/default.nix
+++ b/dhall-nix/nix/dhall-nix.nix
@@ -5,7 +5,7 @@
 mkDerivation {
   pname = "dhall-nix";
   version = "1.1.3";
-  src = ./.;
+  src = ./..;
   isLibrary = true;
   isExecutable = true;
   libraryHaskellDepends = [
diff --git a/dhall-nix/dhall.nix b/dhall-nix/nix/dhall.nix
similarity index 100%
rename from dhall-nix/dhall.nix
rename to dhall-nix/nix/dhall.nix
diff --git a/dhall-nix/nix/fetchNixpkgs.nix b/dhall-nix/nix/fetchNixpkgs.nix
new file mode 100644
index 0000000..478c25d
--- /dev/null
+++ b/dhall-nix/nix/fetchNixpkgs.nix
@@ -0,0 +1,49 @@
+{ rev                             # The Git revision of nixpkgs to fetch
+, sha256                          # The SHA256 of the downloaded data
+, outputSha256 ? null             # The SHA256 fixed-output hash
+, system ? builtins.currentSystem # This is overridable if necessary
+}:
+
+if (0 <= builtins.compareVersions builtins.nixVersion "1.12")
+
+# In Nix 1.12, we can just give a `sha256` to `builtins.fetchTarball`.
+then (
+  builtins.fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+    sha256 = outputSha256;
+  })
+
+# This hack should at least work for Nix 1.11
+else (
+  (rec {
+    tarball = import <nix/fetchurl.nix> {
+      url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+      inherit sha256;
+    };
+
+    builtin-paths = import <nix/config.nix>;
+      
+    script = builtins.toFile "nixpkgs-unpacker" ''
+      "$coreutils/mkdir" "$out"
+      cd "$out"
+      "$gzip" --decompress < "$tarball" | "$tar" -x --strip-components=1
+    '';
+
+    nixpkgs = builtins.derivation ({
+      name = "nixpkgs-${builtins.substring 0 6 rev}";
+
+      builder = builtins.storePath builtin-paths.shell;
+
+      args = [ script ];
+
+      inherit tarball system;
+
+      tar       = builtins.storePath builtin-paths.tar;
+      gzip      = builtins.storePath builtin-paths.gzip;
+      coreutils = builtins.storePath builtin-paths.coreutils;
+    } // (if null == outputSha256 then { } else {
+      outputHashMode = "recursive";
+      outputHashAlgo = "sha256";
+      outputHash = outputSha256;
+    }));
+  }).nixpkgs)
diff --git a/dhall-nix/prettyprinter.nix b/dhall-nix/prettyprinter.nix
deleted file mode 100644
index 5180605..0000000
--- a/dhall-nix/prettyprinter.nix
+++ /dev/null
@@ -1,25 +0,0 @@
-{ mkDerivation, ansi-wl-pprint, base, bytestring, containers
-, criterion, deepseq, doctest, mtl, pgp-wordlist, QuickCheck
-, random, stdenv, tasty, tasty-hunit, tasty-quickcheck
-, template-haskell, text, transformers
-}:
-mkDerivation {
-  pname = "prettyprinter";
-  version = "1.2.0.1";
-  sha256 = "11397b182138efc8f7b09a70873093fb565d070e4c8f92cdde9e601bcd5a0566";
-  isLibrary = true;
-  isExecutable = true;
-  libraryHaskellDepends = [ base text ];
-  executableHaskellDepends = [ base template-haskell text ];
-  testHaskellDepends = [
-    base bytestring doctest pgp-wordlist tasty tasty-hunit
-    tasty-quickcheck text
-  ];
-  benchmarkHaskellDepends = [
-    ansi-wl-pprint base containers criterion deepseq mtl QuickCheck
-    random text transformers
-  ];
-  homepage = "http://github.com/quchen/prettyprinter";
-  description = "A modern, easy to use, well-documented, extensible prettyprinter";
-  license = stdenv.lib.licenses.bsd2;
-}
diff --git a/dhall-nix/release.nix b/dhall-nix/release.nix
index b33cb5f..f60d742 100644
--- a/dhall-nix/release.nix
+++ b/dhall-nix/release.nix
@@ -1,52 +1,38 @@
-# You can build this repository using Nix by running:
-#
-#     $ nix-build -A dhall-nix release.nix
-#
-# You can also open up this repository inside of a Nix shell by running:
-#
-#     $ nix-shell -A dhall-nix.env release.nix
-#
-# ... and then Nix will supply the correct Haskell development environment for
-# you
 let
+  fetchNixpkgs = import ./nix/fetchNixpkgs.nix;
+
+  nixpkgs = fetchNixpkgs {
+    rev = "804060ff9a79ceb0925fe9ef79ddbf564a225d47";
+
+    sha256 = "01pb6p07xawi60kshsxxq1bzn8a0y4s5jjqvhkwps4f5xjmmwav3";
+
+    outputSha256 = "0ga345hgw6v2kzyhvf5kw96hf60mx5pbd9c4qj5q4nan4lr7nkxn";
+  };
+
   config = {
     packageOverrides = pkgs: {
       haskellPackages = pkgs.haskellPackages.override {
         overrides = haskellPackagesNew: haskellPackagesOld: {
-          dhall = haskellPackagesNew.callPackage ./dhall.nix { };
+          dhall = haskellPackagesNew.callPackage ./nix/dhall.nix { };
 
           dhall-nix =
-            pkgs.haskell.lib.justStaticExecutables
-              (haskellPackagesNew.callPackage ./default.nix { });
+            pkgs.haskell.lib.failOnAllWarnings
+              (pkgs.haskell.lib.justStaticExecutables
+                (haskellPackagesNew.callPackage ./nix/dhall-nix.nix { })
+              );
 
-          prettyprinter = haskellPackagesNew.callPackage ./prettyprinter.nix { };
+          formatting = haskellPackagesOld.formatting_6_3_0;
 
-          formatting = haskellPackagesNew.callPackage ./formatting.nix { };
+          prettyprinter = haskellPackagesOld.prettyprinter_1_2_0_1;
         };
       };
     };
   };
 
   pkgs =
-    import <nixpkgs> { inherit config; };
+    import nixpkgs { inherit config; };
 
-  # Convert a Dhall expression (represented as a string) to the equivalent Nix
-  # expression
-  dhallToNix = code :
-    let
-      file = builtins.toFile "dhall-expr" code;
-
-      drv = pkgs.stdenv.mkDerivation {
-        name = "dhall-expr-as-nix";
-
-        buildCommand = ''
-          dhall-to-nix <<< "${file}" > $out
-        '';
-
-        buildInputs = [ pkgs.haskellPackages.dhall-nix ];
-      };
-    in
-      import "${drv}";
+  inherit (pkgs) dhallToNix;
 
 in
   { dhall-nix = pkgs.haskellPackages.dhall-nix;