diff --git a/fetch-nixpkgs.nix b/fetch-nixpkgs.nix
deleted file mode 100644
index bf12e8b..0000000
--- a/fetch-nixpkgs.nix
+++ /dev/null
@@ -1,60 +0,0 @@
-{ rev                             # The Git revision of nixpkgs to fetch
-, sha256                          # The SHA256 of the downloaded data
-, outputSha256 ? null             # The SHA256 output hash
-, system ? builtins.currentSystem # This is overridable if necessary
-}:
-
-with {
-  ifThenElse = { bool, thenValue, elseValue }: (
-    if bool then thenValue else elseValue);
-};
-
-ifThenElse {
-  bool = (0 <= builtins.compareVersions builtins.nixVersion "1.12");
-
-  # In Nix 1.12, we can just give a `sha256` to `builtins.fetchTarball`.
-  thenValue = (
-    builtins.fetchTarball {
-      url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
-
-      # builtins.fetchTarball does not need the sha256 hash of the
-      # packed and compressed tarball but it _does_ need the
-      # fixed-output sha256 hash.
-      sha256 = outputSha256;
-    });
-
-  # This hack should at least work for Nix 1.11
-  elseValue = (
-    (rec {
-      tarball = import <nix/fetchurl.nix> {
-        url = "https://github.com/NixOS/nixpkgs/archive/${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/grpc-haskell.cabal b/grpc-haskell.cabal
index 50e5d27..d0f91f1 100644
--- a/grpc-haskell.cabal
+++ b/grpc-haskell.cabal
@@ -199,7 +199,7 @@ test-suite tests
     , transformers
     , safe
     , clock >=0.6.0 && <0.8.0
-    , turtle >= 1.2.0
+    , turtle >= 1.5.0
     , text
     , QuickCheck >=2.8 && <3.0
   other-modules:
diff --git a/nix/base-compat-batteries.nix b/nix/base-compat-batteries.nix
new file mode 100644
index 0000000..a31c6c0
--- /dev/null
+++ b/nix/base-compat-batteries.nix
@@ -0,0 +1,14 @@
+{ mkDerivation, base, base-compat, bifunctors, contravariant, hspec
+, QuickCheck, stdenv
+}:
+mkDerivation {
+  pname = "base-compat-batteries";
+  version = "0.10.5";
+  sha256 = "175dcfd1453bd02ec955c05181cbf4278af145183b5899c62d3be29d866170ee";
+  libraryHaskellDepends = [
+    base base-compat bifunctors contravariant
+  ];
+  testHaskellDepends = [ base hspec QuickCheck ];
+  description = "base-compat with extra batteries";
+  license = stdenv.lib.licenses.mit;
+}
diff --git a/nix/base-compat.nix b/nix/base-compat.nix
new file mode 100644
index 0000000..2debdf8
--- /dev/null
+++ b/nix/base-compat.nix
@@ -0,0 +1,9 @@
+{ mkDerivation, base, stdenv, unix }:
+mkDerivation {
+  pname = "base-compat";
+  version = "0.10.5";
+  sha256 = "990aea21568956d44ab018c5dbfbaea014b9a0d5295d29ca7550149419a6fb41";
+  libraryHaskellDepends = [ base unix ];
+  description = "A compatibility layer for base";
+  license = stdenv.lib.licenses.mit;
+}
diff --git a/nix/contravariant.nix b/nix/contravariant.nix
new file mode 100644
index 0000000..f929b4c
--- /dev/null
+++ b/nix/contravariant.nix
@@ -0,0 +1,10 @@
+{ mkDerivation, base, StateVar, stdenv, transformers }:
+mkDerivation {
+  pname = "contravariant";
+  version = "1.5";
+  sha256 = "6ef067b692ad69ffff294b953aa85f3ded459d4ae133c37896222a09280fc3c2";
+  libraryHaskellDepends = [ base StateVar transformers ];
+  homepage = "http://github.com/ekmett/contravariant/";
+  description = "Contravariant functors";
+  license = stdenv.lib.licenses.bsd3;
+}
diff --git a/nix/fetchNixpkgs.nix b/nix/fetchNixpkgs.nix
new file mode 100644
index 0000000..478c25d
--- /dev/null
+++ b/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/nix/optparse-applicative.nix b/nix/optparse-applicative.nix
index bdfc252..bff5f8c 100644
--- a/nix/optparse-applicative.nix
+++ b/nix/optparse-applicative.nix
@@ -3,8 +3,8 @@
 }:
 mkDerivation {
   pname = "optparse-applicative";
-  version = "0.14.0.0";
-  sha256 = "06iwp1qsq0gjhnhxwyhdhldwvhlgcik6lx5jxpbb40fispyk4nxm";
+  version = "0.14.3.0";
+  sha256 = "72476302fe555a508917b2d7d6121c7b58ea5434cdc08aeb5d4b652e8f0e7663";
   libraryHaskellDepends = [
     ansi-wl-pprint base process transformers transformers-compat
   ];
diff --git a/nix/optparse-generic.nix b/nix/optparse-generic.nix
index 42bc130..91814de 100644
--- a/nix/optparse-generic.nix
+++ b/nix/optparse-generic.nix
@@ -1,13 +1,14 @@
-{ mkDerivation, base, bytestring, optparse-applicative, semigroups
-, stdenv, system-filepath, text, time, transformers, void
+{ mkDerivation, base, bytestring, Only, optparse-applicative
+, semigroups, stdenv, system-filepath, text, time, transformers
+, void
 }:
 mkDerivation {
   pname = "optparse-generic";
-  version = "1.2.1";
-  sha256 = "1dk945dp98mwk1v4y0cky3z0ngmd29nbg6fbaaxnigcrgpbvkjml";
+  version = "1.3.0";
+  sha256 = "80929958606e4a73672b570ba1a23493fbf46268666d14ab5af53623301c398f";
   libraryHaskellDepends = [
-    base bytestring optparse-applicative semigroups system-filepath
-    text time transformers void
+    base bytestring Only optparse-applicative semigroups
+    system-filepath text time transformers void
   ];
   description = "Auto-generate a command-line parser for your datatype";
   license = stdenv.lib.licenses.bsd3;
diff --git a/nix/proto3-wire.nix b/nix/proto3-wire.nix
index b0b85ee..f33755b 100644
--- a/nix/proto3-wire.nix
+++ b/nix/proto3-wire.nix
@@ -6,9 +6,9 @@ mkDerivation {
   pname = "proto3-wire";
   version = "1.0.0";
   src = fetchgit {
-    url = "https://github.com/awakenetworks/proto3-wire.git";
-    sha256 = "14n0d16an782ayipirm5v2mvp58jgf65xvffqzp08p50sksil3gi";
-    rev = "a938330bf794cf3fa05591d03906915df98d157c";
+    url = "git@github.com:awakesecurity/proto3-wire.git";
+    sha256 = "1ps1lijjbwzps2axr94r4k9c6cw9c9s5cy2izf2867hgavxrjs6k";
+    rev = "4f715b29031566878333d81ff0845be766a5d381";
   };
   libraryHaskellDepends = [
     base bytestring cereal containers deepseq hashable QuickCheck safe
diff --git a/nix/swagger2.nix b/nix/swagger2.nix
index f98db58..4ff2414 100644
--- a/nix/swagger2.nix
+++ b/nix/swagger2.nix
@@ -1,25 +1,29 @@
-{ mkDerivation, aeson, aeson-qq, base, base-compat, bytestring
+{ mkDerivation, aeson, base, base-compat-batteries, bytestring
 , Cabal, cabal-doctest, containers, doctest, generics-sop, Glob
 , hashable, hspec, http-media, HUnit, insert-ordered-containers
-, lens, mtl, network, QuickCheck, scientific, stdenv
-, template-haskell, text, time, transformers, transformers-compat
-, unordered-containers, uuid-types, vector
+, lens, mtl, network, QuickCheck, quickcheck-instances, scientific
+, stdenv, template-haskell, text, time, transformers
+, transformers-compat, unordered-containers, utf8-string
+, uuid-types, vector
 }:
 mkDerivation {
   pname = "swagger2";
-  version = "2.1.6";
-  sha256 = "01a29h56vfyw0ilij1pn6qwy50ca90kyj884vs1q52vvh572758j";
+  version = "2.3.0.1";
+  sha256 = "2ee44e05a953c5a25f0e948a89bfdac9940550a31c29fbf2c0135178c58e17d1";
+  revision = "2";
+  editedCabalFile = "0dfxf47mzzb5rmln2smsk0qx53kj1lc3a087r52g2rzz6971zivb";
   setupHaskellDepends = [ base Cabal cabal-doctest ];
   libraryHaskellDepends = [
-    aeson base base-compat bytestring containers generics-sop hashable
-    http-media insert-ordered-containers lens mtl network scientific
-    template-haskell text time transformers transformers-compat
-    unordered-containers uuid-types vector
+    aeson base base-compat-batteries bytestring containers generics-sop
+    hashable http-media insert-ordered-containers lens mtl network
+    scientific template-haskell text time transformers
+    transformers-compat unordered-containers uuid-types vector
   ];
   testHaskellDepends = [
-    aeson aeson-qq base base-compat bytestring containers doctest Glob
+    aeson base base-compat-batteries bytestring containers doctest Glob
     hashable hspec HUnit insert-ordered-containers lens mtl QuickCheck
-    text time unordered-containers vector
+    quickcheck-instances template-haskell text time
+    unordered-containers utf8-string vector
   ];
   homepage = "https://github.com/GetShopTV/swagger2";
   description = "Swagger 2.0 data model";
diff --git a/release.nix b/release.nix
index b957772..f055daf 100644
--- a/release.nix
+++ b/release.nix
@@ -58,13 +58,24 @@
 # run:
 #
 #     $ cabal2nix path/to/dependency/repo > nix/${package-name}.nix
+
 let
-  nixpkgs = import ./nixpkgs.nix;
+  fetchNixpkgs = import ./nix/fetchNixpkgs.nix;
+
+  nixpkgs = fetchNixpkgs {
+   rev          = "a8ff2616603a6ff6bfb060368c12a973c8e007f6";
+   sha256       = "15l57ra62w9imqv3cfx9qp1fag3mqp95x0hdh81cqjb663qxihlg";
+   outputSha256 = "1nkpbwdx1jgr2pv5arllk6k56h3xc61jal7qi66g21qsx6daf0g3";
+  };
+
   config = {
     packageOverrides = pkgs: rec {
       protobuf3_2NoCheck =
         pkgs.stdenv.lib.overrideDerivation
-          pkgs.pythonPackages.protobuf3_2
+          (pkgs.pythonPackages.callPackage "${nixpkgs}/pkgs/development/python-modules/protobuf" {
+            disabled = false;
+            protobuf = pkgs.protobuf3_4;
+          })
           (oldAttrs : {doCheck = false; doInstallCheck = false;});
 
       cython = pkgs.pythonPackages.buildPythonPackage rec {
@@ -189,21 +200,15 @@ let
 
       haskellPackages = pkgs.haskellPackages.override {
         overrides = haskellPackagesNew: haskellPackagesOld: rec {
-          aeson =
-            pkgs.haskell.lib.dontCheck
-              (haskellPackagesNew.callPackage ./nix/aeson.nix {});
 
-          cabal-doctest =
-            haskellPackagesNew.callPackage ./nix/cabal-doctest.nix { };
+          base-compat-batteries =
+            haskellPackagesNew.callPackage ./nix/base-compat-batteries.nix { };
 
-          insert-ordered-containers =
-            haskellPackagesNew.callPackage ./nix/insert-ordered-containers.nix { };
+          base-compat =
+            haskellPackagesNew.callPackage ./nix/base-compat.nix { };
 
-          optparse-applicative =
-            haskellPackagesNew.callPackage ./nix/optparse-applicative.nix { };
-
-          optparse-generic =
-            haskellPackagesNew.callPackage ./nix/optparse-generic.nix { };
+          contravariant =
+            haskellPackagesNew.callPackage ./nix/contravariant.nix { };
 
           proto3-wire =
             haskellPackagesNew.callPackage ./nix/proto3-wire.nix { };
@@ -240,7 +245,6 @@ let
                       ]);
 
                     python = pkgs.python.withPackages (pkgs: [
-                      # pkgs.protobuf3_0
                       grpcio-tools
                     ]);
 
@@ -290,10 +294,6 @@ let
 
           swagger2 =
             pkgs.haskell.lib.dontCheck (pkgs.haskell.lib.dontHaddock (haskellPackagesNew.callPackage ./nix/swagger2.nix { }));
-
-          turtle =
-            haskellPackagesNew.callPackage ./nix/turtle.nix { };
-
         };
       };
     };
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..39b5c83
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1 @@
+(import ./release.nix).grpc-haskell.env