diff --git a/language.cabal b/language.cabal
index 7ecaefc..6fc24c9 100644
--- a/language.cabal
+++ b/language.cabal
@@ -68,10 +68,10 @@ executable language
     -- other-extensions:
 
     -- Other library packages from which modules are imported.
-    build-depends:    base ^>=4.17.0.0
+    build-depends:    base ^>=4.16.3.0
 
     -- Directories containing source files.
-    hs-source-dirs:   app
+    hs-source-dirs:   src
 
     -- Base language which the package is written in.
     default-language: GHC2021
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..cc84b62
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,14 @@
+let
+  pkgs = import <nixpkgs> { }; # pin the channel to ensure reproducibility!
+in
+pkgs.haskellPackages.developPackage {
+  root = ./.;
+  withHoogle = true;
+  modifier = drv:
+  pkgs.haskell.lib.addBuildTools drv (
+    (with pkgs; [ hlint haskell-language-server ghc ])
+    ++
+    (with pkgs.haskellPackages; [ cabal-install stylish-haskell ])
+  );
+}
+
diff --git a/app/Main.hs b/src/Main.hs
similarity index 100%
rename from app/Main.hs
rename to src/Main.hs