diff --git a/shell.nix b/shell.nix
line changes: +3/-4
index 1fea958..06a3cf1
--- a/shell.nix
+++ b/shell.nix

@@ -4,10 +4,9 @@ let
   ghc = "ghc92";
   haskellPackages = pkgs.haskell.packages.${ghc};
 
-in haskellPackages.shellFor {
-  packages = p: [ ];
-  buildInputs = [
-    haskellPackages.cabal-install
+in pkgs.mkShell {
+  nativeBuildInputs = [
+    (haskellPackages.ghcWithPackages (p: with p; [ typed-process ]))
     haskellPackages.ghcid
     haskellPackages.haskell-language-server
 

diff --git a/sizer.hs b/sizer.hs
line changes: +8/-0
index 0000000..edb1b2a
--- /dev/null
+++ b/sizer.hs

@@ -0,0 +1,8 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import System.Process.Typed (runProcess_)
+
+main :: IO ()
+main = do
+  runProcess_ "false"
+