diff --git a/flake.nix b/flake.nix
index f8680278e..247665dc0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -39,6 +39,7 @@
           ppx_assert
           ppx_sexp_conv
           ppx_deriving
+          ppx_optcomp
           ppx_import
           sexplib
           ppx_yojson_conv