diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6b5566e..2335494 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,6 +15,8 @@ jobs:
       matrix:
         os:
           - ubuntu-latest
+          - macos-latest
+          - windows-latest
         ocaml-compiler:
           - "4.14"
           - "5.1"
diff --git a/mlx/pp.ml b/mlx/pp.ml
index 3f50824..bee5892 100644
--- a/mlx/pp.ml
+++ b/mlx/pp.ml
@@ -53,6 +53,7 @@ let () =
           Format.printf "%a@." Compiler_pprintast.structure str
         else
           let oc = stdout in
+          Out_channel.set_binary_mode oc true;
           output_string oc
             Ppxlib_ast.Compiler_version.Ast.Config.ast_impl_magic_number;
           output_value oc fname;