diff --git a/flake.nix b/flake.nix
index 1a8526a..d045dce 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,45 +3,68 @@
 
   inputs.nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
 
-  outputs = { self, nixpkgs }: {
+  outputs = { self, nixpkgs }:
+    let
+      overlay = import ./nix/overlay.nix;
+      settings = import ./nix/settings.nix;
+      haskellDeps = import ./nix/haskell-deps.nix;
 
-    packages.x86_64-linux.utoy =
-      let
-        overlay = import ./nix/overlay.nix;
-        pkgs = nixpkgs.legacyPackages.x86_64-linux.extend overlay;
-        settings = import ./nix/settings.nix;
-        haskellDeps = import ./nix/haskell-deps.nix;
+      pkgs = nixpkgs.legacyPackages.x86_64-linux.extend overlay;
+      haskellPackages = pkgs.haskell.packages."${settings.ghc}";
 
-        haskellPackages = pkgs.haskell.packages."${settings.ghc}";
+      stack = pkgs.stdenv.mkDerivation {
+        pname = "stack";
+        version = "0";
+        dontUnpack = true;
+        dontConfigure = true;
+        dontBuild = true;
+        nativeBuildInputs = [ pkgs.makeWrapper ];
+        installPhase = ''
+          makeWrapper ${pkgs.stack}/bin/stack $out/bin/stack \
+            --add-flags '--no-nix --no-install-ghc'
+        '';
+      };
+    in {
+      packages.x86_64-linux.stack = stack;
+      packages.x86_64-linux.utoy =
+        let
+          utoy =
+            { mkDerivation }:
+            mkDerivation {
+              version = "0.5";
+              pname = "utoy";
+              license = pkgs.lib.licenses.mit;
+              src =
+                let
+                  buildFiles = [
+                    ./LICENSE
+                    ./utoy.cabal
+                    ./Setup.hs
+                    ./app
+                    ./src
+                    ./static
+                    ./test
+                  ];
+                in
+                  pkgs.lib.sources.cleanSourceWith {
+                    src = ./.;
+                    filter = path: _type: pkgs.lib.any (prefix: pkgs.lib.hasPrefix (toString prefix) path) buildFiles;
+                  };
 
-        utoy =
-          { mkDerivation }:
-          mkDerivation {
-            version = "0.5";
-            pname = "utoy";
-            license = pkgs.lib.licenses.mit;
-            src =
-              let
-                buildFiles = [
-                  ./LICENSE
-                  ./utoy.cabal
-                  ./Setup.hs
-                  ./app
-                  ./src
-                  ./static
-                  ./test
-                ];
-              in
-                pkgs.lib.sources.cleanSourceWith {
-                  src = ./.;
-                  filter = path: _type: pkgs.lib.any (prefix: pkgs.lib.hasPrefix (toString prefix) path) buildFiles;
-                };
+              libraryHaskellDepends = haskellDeps haskellPackages;
+            };
+        in
+          pkgs.haskell.lib.justStaticExecutables (haskellPackages.callPackage utoy {});
 
-            libraryHaskellDepends = haskellDeps haskellPackages;
-          };
-      in
-        pkgs.haskell.lib.justStaticExecutables (haskellPackages.callPackage utoy {});
+      packages.x86_64-linux.default = self.packages.x86_64-linux.utoy;
 
-    packages.x86_64-linux.default = self.packages.x86_64-linux.utoy;
+      devShells.default = pkgs.mkShell {
+        buildInputs = [
+          stack
+        ];
+        shellHook = ''
+          PS1+=" (utoy)";
+        '';
+      };
   };
 }
diff --git a/shell.nix b/shell.nix
index e95d7f9..04a9521 100644
--- a/shell.nix
+++ b/shell.nix
@@ -5,10 +5,6 @@ let
   haskellPackages = pkgs.haskell.packages."${settings.ghc}";
 
   tools = with pkgs; [
-    # nix tools
-    niv
-    nix-tree
-
     # haskell tools
     stack
     (haskellPackages.ghcWithPackages haskellDeps)