diff --git a/users/youwen/common/neovim/default.nix b/users/youwen/common/neovim/default.nix
index d9c1758..119ea0b 100644
--- a/users/youwen/common/neovim/default.nix
+++ b/users/youwen/common/neovim/default.nix
@@ -524,6 +524,7 @@
           nix = ["alejandra"];
           svelte = ["prettier"];
           rust = ["rustfmt"];
+          haskell = ["fourmolu"];
           "*" = ["codespell"];
           "_" = ["trim_whitespace"];
         };