diff --git a/lib/cmdlang_to_base/test/test__param.ml b/lib/cmdlang_to_base/test/test__param.ml
index d56077b..ccb1a00 100644
--- a/lib/cmdlang_to_base/test/test__param.ml
+++ b/lib/cmdlang_to_base/test/test__param.ml
@@ -1,6 +1,6 @@
 let%expect_test "param" =
   let config = Cmdlang_to_base.Translate.Config.create () in
-  let conv (type a) param sexp_of_a params =
+  let conv (type a) (param : a Cmdlang.Command.Param.t) (sexp_of_a : a -> Sexp.t) params =
     let conv = Cmdlang_to_base.Translate.param param ~config in
     List.iter params ~f:(fun str ->
       print_s [%sexp (str : string), (Command.Arg_type.parse conv str : a Or_error.t)])
diff --git a/lib/cmdlang_to_climate/test/test__param.ml b/lib/cmdlang_to_climate/test/test__param.ml
index 2ac64c8..63d5c6b 100644
--- a/lib/cmdlang_to_climate/test/test__param.ml
+++ b/lib/cmdlang_to_climate/test/test__param.ml
@@ -1,7 +1,7 @@
 module Command = Cmdlang.Command
 
 let%expect_test "param" =
-  let conv (type a) param sexp_of_a params =
+  let conv (type a) (param : a Command.Param.t) (sexp_of_a : a -> Sexp.t) params =
     let conv = Cmdlang_to_climate.Translate.param param in
     List.iter params ~f:(fun str ->
       print_s [%sexp (str : string), (conv.parse str : (a, [ `Msg of string ]) Result.t)])
diff --git a/lib/cmdlang_to_cmdliner/test/test__param.ml b/lib/cmdlang_to_cmdliner/test/test__param.ml
index a845b4e..cd31571 100644
--- a/lib/cmdlang_to_cmdliner/test/test__param.ml
+++ b/lib/cmdlang_to_cmdliner/test/test__param.ml
@@ -1,7 +1,7 @@
 module Command = Cmdlang.Command
 
 let%expect_test "param" =
-  let conv (type a) param sexp_of_a params =
+  let conv (type a) (param : a Command.Param.t) (sexp_of_a : a -> Sexp.t) params =
     let conv = Cmdlang_to_cmdliner.Translate.param param in
     List.iter params ~f:(fun str ->
       print_s