diff --git a/default.nix b/default.nix
index c0aed56..c535b87 100644
--- a/default.nix
+++ b/default.nix
@@ -10,6 +10,7 @@ let
 
   pkgs = nixpkgs.haskell.packages;
   lib = nixpkgs.haskell.lib;
+  callCabal2nix = nixpkgs.haskell.packages.${compiler}.callCabal2nix;
 
   doHaddock = if haddock
     then lib.doHaddock
@@ -23,12 +24,23 @@ let
   doDev = if dev
     then drv: lib.appendConfigureFlag drv "--ghc-option -Werror"
     else nixpkgs.lib.id;
+  docNoSeprateOutput = drv: lib.overrideCabal drv (drv: { enableSeparateDocOutput = false; });
+  srcFilter = src: path: type:
+    let relPath = nixpkgs.lib.removePrefix (toString src + "/") (toString path);
+    in 
+       nixpkgs.lib.hasPrefix "src" relPath
+    || nixpkgs.lib.hasPrefix "test" relPath
+    || nixpkgs.lib.any
+        (a: a == relPath)
+        [ "Setup.hs" "cabal.project" "ChangeLog.md" "free-category.cabal" "LICENSE"];
 
-  free-category = doDev(doHaddock(doTest(doBench(
-    pkgs.${compiler}.callPackage ./pkg.nix
-      { inherit nixpkgs; }))));
-  examples = doDev(doHaddock(doTest(doBench(
-    pkgs.${compiler}.callPackage ./examples/pkg.nix
-      { inherit free-category nixpkgs; }))));
-in
-{ inherit free-category examples; }
+  free-category = docNoSeprateOutput(doDev(doHaddock(doTest(doBench(
+    lib.overrideCabal (callCabal2nix "free-category" ./.  {})
+      (drv: {src = nixpkgs.lib.cleanSourceWith { filter = srcFilter drv.src; src = drv.src; };})
+  )))));
+  examples = docNoSeprateOutput(doDev(doHaddock(doTest(doBench(
+    lib.overrideCabal (callCabal2nix "examples" ./examples { inherit free-category; })
+      (drv: {src = nixpkgs.lib.sourceFilesBySuffices drv.src [ ".hs" "LICENSE" "ChangeLog.md" "examples.cabal" ];})
+  )))));
+
+in { inherit free-category examples; }
diff --git a/examples/pkg.nix b/examples/pkg.nix
deleted file mode 100644
index d656619..0000000
--- a/examples/pkg.nix
+++ /dev/null
@@ -1,23 +0,0 @@
-{ nixpkgs
-, mkDerivation
-, base
-, free-category
-, free-algebras
-, QuickCheck
-, stdenv
-}:
-mkDerivation {
-  pname = "free-category-examples";
-  version = "0.0.1.0";
-  src = nixpkgs.lib.sourceFilesBySuffices ./.
-    [ ".hs" "LICENSE" "ChangeLog.md" "examples.cabal" ];
-  libraryHaskellDepends = [
-    base
-    free-category
-    free-algebras
-    QuickCheck
-  ];
-  libraryToolDepends = [ ];
-  license = stdenv.lib.licenses.mpl20;
-  enableSeparateDocOutput = false;
-}
diff --git a/pkg.nix b/pkg.nix
deleted file mode 100644
index 62edfb5..0000000
--- a/pkg.nix
+++ /dev/null
@@ -1,33 +0,0 @@
-{ mkDerivation
-, nixpkgs
-, stdenv
-, base
-, free-algebras
-}:
-let
-  lib = nixpkgs.lib;
-  srcFilter = src: path: type:
-    let relPath = lib.removePrefix (toString src + "/") (toString path);
-    in 
-       lib.hasPrefix "src" relPath
-    || lib.hasPrefix "test" relPath
-    || lib.any
-        (a: a == relPath)
-        [ "Setup.hs" "cabal.project" "ChangeLog.md" "free-category.cabal" "LICENSE"];
-in
-mkDerivation {
-  pname = "free-category";
-  version = "0.0.1.0";
-  src = lib.cleanSourceWith { filter = srcFilter ./.; src = ./.; };
-  libraryHaskellDepends = [
-    base
-    free-algebras
-  ];
-  libraryToolDepends = [ ];
-  testHaskellDepends = [
-    base
-  ];
-  homepage = "https://github.com/coot/free-algebras#readme";
-  license = stdenv.lib.licenses.mpl20;
-  enableSeparateDocOutput = false;
-}