diff --git a/default.nix b/default.nix
index cc1d392..eea5386 100644
--- a/default.nix
+++ b/default.nix
@@ -23,6 +23,7 @@ in
         haddock
         cabal-install
         hlint
+        stylish-haskell
         pkgs.python3Packages.asn1ate
       ];
   };