diff --git a/unikernel/unikernel.ml b/unikernel/unikernel.ml
index a9624814..2e2876fc 100644
--- a/unikernel/unikernel.ml
+++ b/unikernel/unikernel.ml
@@ -44,28 +44,17 @@ struct
   module Assets = struct
     module Assets_ro = Keys_ro
 
-    let ( let*$ ) = Lwt_result.bind
+    let ( let*? ) = Lwt_result.bind
+    let ( let+? ) x f = Lwt_result.map f x
     let map_err_to_string = map_err_to_string Assets_ro.pp_error
 
-    let get_dir l name =
-      l
-      |> List.find_opt (fun (k, t) ->
-          Mirage_kv.Key.(equal (v name) k) && t = `Dictionary)
-      |> Option.map fst
-      |> Option.to_result ~none:(`Msg (Fmt.str "missing `%s` directory" name))
-      |> Lwt_result.lift
-
     let get_subdirs ro k =
-      let*$ keys = Assets_ro.list ro k |> map_err_to_string in
-      List.filter (fun (_, t) -> t = `Dictionary) keys
-      |> List.map fst
-      |> Lwt_result.return
+      let+? keys = Assets_ro.list ro k |> map_err_to_string in
+      List.filter (fun (_, t) -> t = `Dictionary) keys |> List.map fst
 
     let get_values ro k =
-      let*$ keys = Assets_ro.list ro k |> map_err_to_string in
-      List.filter (fun (_, t) -> t = `Value) keys
-      |> List.map fst
-      |> Lwt_result.return
+      let+? keys = Assets_ro.list ro k |> map_err_to_string in
+      List.filter (fun (_, t) -> t = `Value) keys |> List.map fst
 
     let find keys name =
       keys
@@ -74,15 +63,15 @@ struct
       |> Lwt_result.lift
 
     let assets ro =
-      let*$ base_dir = get_subdirs ro Mirage_kv.Key.empty in
-      let*$ terms_dir = find base_dir "terms" in
-      let*$ privacy_dir = find base_dir "privacy" in
-      let*$ terms_subdirs = get_subdirs ro terms_dir in
-      let*$ privacy_subdirs = get_subdirs ro privacy_dir in
-      let*$ _terms_files =
+      let*? base_dir = get_subdirs ro Mirage_kv.Key.empty in
+      let*? terms_dir = find base_dir "terms" in
+      let*? privacy_dir = find base_dir "privacy" in
+      let*? terms_subdirs = get_subdirs ro terms_dir in
+      let*? privacy_subdirs = get_subdirs ro privacy_dir in
+      let*? _terms_files =
         terms_subdirs |> Lwt_list.map_s (get_values ro) |> Lwt_result.ok
       in
-      let*$ _privacy_files =
+      let*? _privacy_files =
         privacy_subdirs |> Lwt_list.map_s (get_values ro) |> Lwt_result.ok
       in
       Lwt_result.return ()