diff --git a/sherlodoc/store/storage_marshal.ml b/sherlodoc/store/storage_marshal.ml
index 6f913a0947..59aa6f19f6 100644
--- a/sherlodoc/store/storage_marshal.ml
+++ b/sherlodoc/store/storage_marshal.ml
@@ -6,6 +6,4 @@ let save ~db t = Marshal.to_channel db t []
 
 let load name =
   let file = open_in name in
-  let t = Marshal.from_channel file in
-  close_in file ;
-  [ t ]
+  Fun.protect ~finally:(fun () -> close_in file) (fun () -> [ Marshal.from_channel file ])
diff --git a/src/driver/library_names.ml b/src/driver/library_names.ml
index c690f48034..c9dc4eed45 100644
--- a/src/driver/library_names.ml
+++ b/src/driver/library_names.ml
@@ -1,3 +1,5 @@
+open Bos
+
 (** To extract the library names for a given package, without using dune, we
 
     1. parse the META file of the package with ocamlfind to see which libraries
@@ -44,9 +46,11 @@ let read_libraries_from_pkg_defs ~library_name pkg_defs =
 
 let process_meta_file file =
   let () = Format.eprintf "process_meta_file: %s\n%!" (Fpath.to_string file) in
-  let ic = open_in (Fpath.to_string file) in
   let meta_dir = Fpath.parent file in
-  let meta = Fl_metascanner.parse ic in
+  let meta =
+    OS.File.with_ic file (fun ic () -> Fl_metascanner.parse ic) ()
+    |> Result.get_ok
+  in
   let base_library_name =
     if Fpath.basename file = "META" then Fpath.parent file |> Fpath.basename
     else Fpath.get_ext file
@@ -116,7 +120,7 @@ let directories v =
           (* NB. topkg installs a META file that points to a ../topkg-care directory
               that is installed by the topkg-care package. We filter that out here,
               though I've not thought of a good way to sort out the `topkg-care` package *)
-          match Bos.OS.Dir.exists dir with
+          match OS.Dir.exists dir with
           | Ok true -> Fpath.Set.add dir acc
           | _ -> acc))
     Fpath.Set.empty libraries
diff --git a/src/odoc/bin/dune b/src/odoc/bin/dune
index a86be42a68..29a5b158e2 100644
--- a/src/odoc/bin/dune
+++ b/src/odoc/bin/dune
@@ -3,8 +3,6 @@
  (package odoc)
  (public_name odoc)
  (libraries compatcmdliner odoc_model odoc_odoc)
- (flags
-  (:standard -open StdLabels))
  (instrumentation
   (backend landmarks --auto))
  (instrumentation
diff --git a/src/odoc/bin/main.ml b/src/odoc/bin/main.ml
index cb802e00b1..eea2b62cdc 100644
--- a/src/odoc/bin/main.ml
+++ b/src/odoc/bin/main.ml
@@ -3,6 +3,8 @@
    It would make the interaction with jenga nicer if we could specify a file to
    output the result to. *)
 
+open Odoc_utils
+module List = ListLabels
 open Odoc_odoc
 open Compatcmdliner
 
@@ -40,7 +42,7 @@ let convert_fpath =
 
 let convert_named_root =
   let parse inp =
-    match Astring.String.cuts inp ~sep:":" with
+    match String.cuts inp ~sep:":" with
     | [ s1; s2 ] -> Result.Ok (s1, Fs.Directory.of_string s2)
     | _ -> Error (`Msg "")
   in
@@ -190,7 +192,7 @@ module Compile : sig
 end = struct
   let has_page_prefix file =
     file |> Fs.File.basename |> Fs.File.to_string
-    |> Astring.String.is_prefix ~affix:"page-"
+    |> String.is_prefix ~affix:"page-"
 
   let unique_id =
     let doc = "For debugging use" in
@@ -411,7 +413,7 @@ module Compile_impl = struct
   let output_file output_dir parent_id input =
     let name =
       Fs.File.basename input |> Fpath.set_ext "odoc" |> Fs.File.to_string
-      |> Astring.String.Ascii.uncapitalize
+      |> String.Ascii.uncapitalize
     in
     let name = prefix ^ name in
 
@@ -1150,7 +1152,7 @@ module Odoc_html_args = struct
       || str.[0] = '/'
 
     let conv_rel_dir rel =
-      let l = Astring.String.cuts ~sep:"/" rel in
+      let l = String.cuts ~sep:"/" rel in
       List.fold_left
         ~f:(fun acc seg ->
           Some Odoc_document.Url.Path.{ kind = `Page; parent = acc; name = seg })
@@ -1164,7 +1166,7 @@ module Odoc_html_args = struct
           let last_char = str.[String.length str - 1] in
           let str =
             if last_char <> '/' then str
-            else String.sub str ~pos:0 ~len:(String.length str - 1)
+            else String.with_range ~len:(String.length str - 1) str
           in
           `Ok
             (if is_absolute str then (Absolute str : uri)
@@ -1186,7 +1188,7 @@ module Odoc_html_args = struct
         if String.length str = 0 then `Error "invalid URI"
         else
           let conv_rel_file rel =
-            match Astring.String.cut ~rev:true ~sep:"/" rel with
+            match String.cut ~rev:true ~sep:"/" rel with
             | Some (before, after) ->
                 let base = conv_rel_dir before in
                 Odoc_document.Url.Path.
@@ -1268,7 +1270,7 @@ module Odoc_html_args = struct
   let remap =
     let convert_remap =
       let parse inp =
-        match Astring.String.cut ~sep:":" inp with
+        match String.cut ~sep:":" inp with
         | Some (orig, mapped) -> Result.Ok (orig, mapped)
         | _ -> Error (`Msg "Map must be of the form '<orig>:https://...'")
       and print fmt (orig, mapped) = Format.fprintf fmt "%s:%s" orig mapped in
@@ -1289,18 +1291,12 @@ module Odoc_html_args = struct
         match remap_file with
         | None -> remap
         | Some f ->
-            let ic = open_in f in
-            let rec loop acc =
-              match input_line ic with
-              | exception _ ->
-                  close_in ic;
-                  acc
-              | line -> (
-                  match Astring.String.cut ~sep:":" line with
-                  | Some (orig, mapped) -> loop ((orig, mapped) :: acc)
-                  | None -> loop acc)
-            in
-            loop []
+            Io_utils.fold_lines f
+              (fun line acc ->
+                match String.cut ~sep:":" line with
+                | Some (orig, mapped) -> (orig, mapped) :: acc
+                | None -> acc)
+              []
       in
       let html_config =
         Odoc_html.Config.v ~theme_uri ~support_uri ~search_uris ~semantic_uris
diff --git a/src/odoc/classify.cppo.ml b/src/odoc/classify.cppo.ml
index 0e6cc2f414..417bf817ef 100644
--- a/src/odoc/classify.cppo.ml
+++ b/src/odoc/classify.cppo.ml
@@ -3,8 +3,8 @@
 (* Given a directory with cmis, cmas and so on, partition the modules between the libraries *)
 (* open Bos *)
 
+open Odoc_utils
 open Cmo_format
-open Result
 
 module StringSet = Set.Make (String)
 let list_of_stringset x =
@@ -222,12 +222,12 @@ let classify files libraries =
           (fun cur path ->
             if not (Sys.file_exists path) then cur
             else
-              let ic = open_in_bin path in
+              Io_utils.with_open_in_bin path (fun ic ->
               match read_library ic cur with
               | Ok lib -> lib
               | Error (`Msg m) ->
                   Format.eprintf "Error reading library: %s\n%!" m;
-                  cur)
+                  cur))
           (Archive.empty (Fpath.basename lpath)) paths)
       libraries
   in
@@ -411,7 +411,7 @@ let classify files libraries =
       let archive = Archive.filter_by_cmis cmi_names archive_all in
       if Archive.has_modules archive then
         Printf.printf "%s %s\n" a.Archive.name
-          (archive.Archive.modules |> StringSet.elements |> String.concat " "))
+          (archive.Archive.modules |> StringSet.elements |> String.concat ~sep:" "))
     archives;
 
   ()
diff --git a/src/odoc/fs.ml b/src/odoc/fs.ml
index 73bcebf4ac..7cd189f036 100644
--- a/src/odoc/fs.ml
+++ b/src/odoc/fs.ml
@@ -14,6 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
+open Odoc_utils
 open StdLabels
 open Or_error
 
@@ -62,16 +63,6 @@ module File = struct
     | Result.Ok p -> p
 
   let read file =
-    let with_ic ~close ic f =
-      let close ic = try close ic with Sys_error _ -> () in
-      match f ic with
-      | v ->
-          close ic;
-          v
-      | exception e ->
-          close ic;
-          raise e
-    in
     let input_one_shot len ic =
       let buf = Bytes.create len in
       really_input ic buf 0 len;
@@ -95,10 +86,10 @@ module File = struct
     in
     try
       let file = Fpath.to_string file in
-      let is_dash = file = "-" in
-      let ic = if is_dash then stdin else open_in_bin file in
-      let close ic = if is_dash then () else close_in ic in
-      with_ic ~close ic @@ fun ic ->
+      let with_ic k =
+        if file = "-" then k stdin else Io_utils.with_open_in_bin file k
+      in
+      with_ic @@ fun ic ->
       match in_channel_length ic with
       | 0 (* e.g. stdin or /dev/stdin *) -> input_stream file ic
       | len when len <= Sys.max_string_length -> input_one_shot len ic
@@ -108,16 +99,10 @@ module File = struct
     with Sys_error e -> Result.Error (`Msg e)
 
   let copy ~src ~dst =
-    let with_ open_ close filename f =
-      let c = open_ (Fpath.to_string filename) in
-      Odoc_utils.Fun.protect ~finally:(fun () -> close c) (fun () -> f c)
-    in
-    let with_ic = with_ open_in_bin close_in_noerr in
-    let with_oc = with_ open_out_bin close_out_noerr in
     try
-      with_ic src (fun ic ->
+      Io_utils.with_open_in_bin (Fpath.to_string src) (fun ic ->
           mkdir_p (dirname dst);
-          with_oc dst (fun oc ->
+          Io_utils.with_open_out_bin (Fpath.to_string dst) (fun oc ->
               let len = 65536 in
               let buf = Bytes.create len in
               let rec loop () =
diff --git a/src/odoc/html_fragment.ml b/src/odoc/html_fragment.ml
index a5cfdc53de..7189f8b1c7 100644
--- a/src/odoc/html_fragment.ml
+++ b/src/odoc/html_fragment.ml
@@ -1,3 +1,4 @@
+open Odoc_utils
 open Or_error
 
 let from_mld ~xref_base_uri ~resolver ~output ~warnings_options input =
@@ -47,11 +48,8 @@ let from_mld ~xref_base_uri ~resolver ~output ~warnings_options input =
       Odoc_html.Generator.items ~config ~resolve:(Base xref_base_uri)
         (page.Odoc_document.Types.Page.preamble @ page.items)
     in
-    let oc = open_out (Fs.File.to_string output) in
-    let fmt = Format.formatter_of_out_channel oc in
-
+    Io_utils.with_formatter_out (Fs.File.to_string output) @@ fun fmt ->
     Format.fprintf fmt "%a@." (Format.pp_print_list (Tyxml.Html.pp_elt ())) html;
-    close_out oc;
     Ok ()
   in
   match Fs.File.read input with
diff --git a/src/odoc/indexing.ml b/src/odoc/indexing.ml
index 0443978da4..fb2874c2cc 100644
--- a/src/odoc/indexing.ml
+++ b/src/odoc/indexing.ml
@@ -24,11 +24,8 @@ let parse_input_files input =
   >>= fun files -> Ok (List.concat files)
 
 let compile_to_json ~output ~occurrences ~wrap ~simplified hierarchies =
-  let output_channel =
-    Fs.Directory.mkdir_p (Fs.File.dirname output);
-    open_out_bin (Fs.File.to_string output)
-  in
-  let output = Format.formatter_of_out_channel output_channel in
+  Fs.Directory.mkdir_p (Fs.File.dirname output);
+  Io_utils.with_formatter_out (Fs.File.to_string output) @@ fun output ->
   if wrap then Format.fprintf output "let documents = ";
   let all =
     List.fold_left
@@ -47,11 +44,6 @@ let compile_to_json ~output ~occurrences ~wrap ~simplified hierarchies =
        var idx_fuse = new Fuse(documents, options);\n";
   Ok ()
 
-let read_occurrences file =
-  let ic = open_in_bin file in
-  let htbl : Odoc_occurrences.Table.t = Marshal.from_channel ic in
-  htbl
-
 let absolute_normalization p =
   let p =
     if Fpath.is_rel p then Fpath.( // ) (Fpath.v (Sys.getcwd ())) p else p
@@ -70,7 +62,7 @@ let compile out_format ~output ~warnings_options ~occurrences ~roots
   let occurrences =
     match occurrences with
     | None -> None
-    | Some occurrences -> Some (read_occurrences (Fpath.to_string occurrences))
+    | Some occurrences -> Some (Occurrences.read_occurrences occurrences)
   in
   let all_files =
     roots
diff --git a/src/odoc/occurrences.ml b/src/odoc/occurrences.ml
index bd8f91561a..330a50fc4b 100644
--- a/src/odoc/occurrences.ml
+++ b/src/odoc/occurrences.ml
@@ -1,5 +1,5 @@
+open Odoc_utils
 open Or_error
-open Astring
 
 let handle_file file ~f =
   if String.is_prefix ~affix:"impl-" (Fpath.filename file) then
@@ -31,8 +31,7 @@ let count ~dst ~warnings_options:_ directories include_hidden =
   in
   fold_dirs ~dirs:directories ~f ~init:() >>= fun () ->
   Fs.Directory.mkdir_p (Fs.File.dirname dst);
-  let oc = open_out_bin (Fs.File.to_string dst) in
-  Marshal.to_channel oc htbl [];
+  Io_utils.marshal (Fs.File.to_string dst) htbl;
   Ok ()
 
 open Astring
@@ -54,26 +53,24 @@ let parse_input_files input =
     (Ok []) input
   >>= fun files -> Ok (List.concat files)
 
+let read_occurrences file : Odoc_occurrences.Table.t =
+  Io_utils.unmarshal (Fpath.to_string file)
+
 let aggregate files file_list ~warnings_options:_ ~dst =
   try
     parse_input_files file_list >>= fun new_files ->
     let files = files @ new_files in
-    let from_file file : Odoc_occurrences.Table.t =
-      let ic = open_in_bin (Fs.File.to_string file) in
-      Marshal.from_channel ic
-    in
     let occtbl =
       match files with
       | [] -> Odoc_occurrences.Table.v ()
       | file :: files ->
-          let acc = from_file file in
+          let acc = read_occurrences file in
           List.iter
             (fun file ->
-              Odoc_occurrences.aggregate ~tbl:acc ~data:(from_file file))
+              Odoc_occurrences.aggregate ~tbl:acc ~data:(read_occurrences file))
             files;
           acc
     in
-    let oc = open_out_bin (Fs.File.to_string dst) in
-    Marshal.to_channel oc occtbl [];
+    Io_utils.marshal (Fs.File.to_string dst) occtbl;
     Ok ()
   with Sys_error s -> Error (`Msg s)
diff --git a/src/odoc/odoc_file.ml b/src/odoc/odoc_file.ml
index 732994f9a6..d07f1cf824 100644
--- a/src/odoc/odoc_file.ml
+++ b/src/odoc/odoc_file.ml
@@ -14,6 +14,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  *)
 
+open Odoc_utils
 open Odoc_model
 open Or_error
 
@@ -33,10 +34,9 @@ let magic = "odoc-%%VERSION%%"
 (** Exceptions while saving are allowed to leak. *)
 let save_ file f =
   Fs.Directory.mkdir_p (Fs.File.dirname file);
-  let oc = open_out_bin (Fs.File.to_string file) in
-  output_string oc magic;
-  f oc;
-  close_out oc
+  Io_utils.with_open_out_bin (Fs.File.to_string file) (fun oc ->
+      output_string oc magic;
+      f oc)
 
 let save_unit file (root : Root.t) (t : t) =
   save_ file (fun oc ->
@@ -81,26 +81,22 @@ let load_ file f =
   (if Sys.file_exists file then Ok file
    else Error (`Msg (Printf.sprintf "File does not exist")))
   >>= fun file ->
-  let ic = open_in_bin file in
-  let res =
-    try
-      let actual_magic = really_input_string ic (String.length magic) in
-      if actual_magic = magic then f ic
-      else
-        let msg =
-          Printf.sprintf "%s: invalid magic number %S, expected %S\n%!" file
-            actual_magic magic
-        in
-        Error (`Msg msg)
-    with exn ->
+  Io_utils.with_open_in_bin file @@ fun ic ->
+  try
+    let actual_magic = really_input_string ic (String.length magic) in
+    if actual_magic = magic then f ic
+    else
       let msg =
-        Printf.sprintf "Error while unmarshalling %S: %s\n%!" file
-          (match exn with Failure s -> s | _ -> Printexc.to_string exn)
+        Printf.sprintf "%s: invalid magic number %S, expected %S\n%!" file
+          actual_magic magic
       in
       Error (`Msg msg)
-  in
-  close_in ic;
-  res
+  with exn ->
+    let msg =
+      Printf.sprintf "Error while unmarshalling %S: %s\n%!" file
+        (match exn with Failure s -> s | _ -> Printexc.to_string exn)
+    in
+    Error (`Msg msg)
 
 let load file =
   load_ file (fun ic ->
diff --git a/src/odoc/rendering.ml b/src/odoc/rendering.ml
index ff5530a8c0..cccae2143b 100644
--- a/src/odoc/rendering.ml
+++ b/src/odoc/rendering.ml
@@ -1,3 +1,4 @@
+open Odoc_utils
 open Odoc_document
 open Or_error
 open Odoc_model
@@ -53,10 +54,8 @@ let render_document renderer ~sidebar ~output:root_dir ~extra_suffix ~extra doc
   let pages = renderer.Renderer.render extra sidebar doc in
   Renderer.traverse pages ~f:(fun filename content ->
       let filename = prepare ~extra_suffix ~output_dir:root_dir filename in
-      let oc = open_out (Fs.File.to_string filename) in
-      let fmt = Format.formatter_of_out_channel oc in
-      Format.fprintf fmt "%t@?" content;
-      close_out oc)
+      Io_utils.with_formatter_out (Fs.File.to_string filename) @@ fun fmt ->
+      Format.fprintf fmt "%t@?" content)
 
 let render_odoc ~resolver ~warnings_options ~syntax ~renderer ~output extra file
     =
diff --git a/src/odoc/sidebar.ml b/src/odoc/sidebar.ml
index f69eda5561..eaed81956c 100644
--- a/src/odoc/sidebar.ml
+++ b/src/odoc/sidebar.ml
@@ -4,12 +4,9 @@ open Odoc_utils
 let compile_to_json ~output sidebar =
   let json = Odoc_html.Sidebar.to_json sidebar in
   let text = Json.to_string json in
-  let output_channel =
-    Fs.Directory.mkdir_p (Fs.File.dirname output);
-    open_out_bin (Fs.File.to_string output)
-  in
-  Fun.protect ~finally:(fun () -> close_out output_channel) @@ fun () ->
-  Printf.fprintf output_channel "%s" text
+  Fs.Directory.mkdir_p (Fs.File.dirname output);
+  Io_utils.with_open_out_bin (Fs.File.to_string output) @@ fun oc ->
+  Printf.fprintf oc "%s" text
 
 let generate ~marshall ~output ~warnings_options:_ ~index =
   Odoc_file.load_index index >>= fun index ->
diff --git a/src/odoc/support_files.ml b/src/odoc/support_files.ml
index 606e358bb7..366aeda87b 100644
--- a/src/odoc/support_files.ml
+++ b/src/odoc/support_files.ml
@@ -1,3 +1,5 @@
+open Odoc_utils
+
 let should_include ~without_theme file =
   if without_theme then
     match file with
@@ -25,9 +27,7 @@ let write =
       let dir = Fs.File.dirname name in
       Fs.Directory.mkdir_p dir;
       let name = Fs.File.to_string name in
-      let channel = open_out name in
-      output_string channel content;
-      close_out channel)
+      Io_utils.with_open_out name (fun oc -> output_string oc content))
 
 let print_filenames =
   iter_files (fun name _content -> print_endline (Fs.File.to_string name))
diff --git a/src/utils/odoc_utils.ml b/src/utils/odoc_utils.ml
index 642cf8e467..2f8c11888f 100644
--- a/src/utils/odoc_utils.ml
+++ b/src/utils/odoc_utils.ml
@@ -79,4 +79,49 @@ module Tree = Tree
 module Forest = Tree.Forest
 module Json = Json
 
+module Io_utils = struct
+  (** [with_open_*] are resource safe wrappers around opening and closing
+      channels. They are equivalent to the same functions in OCaml 4.14's
+      [In_channel] and [Out_channel]. *)
+
+  let _with_resource res ~close f =
+    Fun.protect ~finally:(fun () -> close res) (fun () -> f res)
+
+  let with_open_in fname f =
+    _with_resource (open_in fname) ~close:close_in_noerr f
+
+  let with_open_in_bin fname f =
+    _with_resource (open_in_bin fname) ~close:close_in_noerr f
+
+  (** Read a file line-by-line by folding [f]. *)
+  let fold_lines fname f acc =
+    _with_resource (open_in fname) ~close:close_in_noerr (fun ic ->
+        let rec loop acc =
+          match input_line ic with
+          | exception End_of_file -> acc
+          | line -> loop (f line acc)
+        in
+        loop acc)
+
+  (** Read a file as a list of lines. *)
+  let read_lines fname =
+    List.rev (fold_lines fname (fun line acc -> line :: acc) [])
+
+  let with_open_out fname f =
+    _with_resource (open_out fname) ~close:close_out_noerr f
+
+  let with_open_out_bin fname f =
+    _with_resource (open_out_bin fname) ~close:close_out_noerr f
+
+  (** Like [with_open_out] but operate on a [Format] buffer. *)
+  let with_formatter_out fname f =
+    with_open_out fname (fun oc -> f (Format.formatter_of_out_channel oc))
+
+  (** Shortcuts for composing [with_open_*] functions and [Marshal]. *)
+  let marshal fname v =
+    with_open_out_bin fname (fun oc -> Marshal.to_channel oc v [])
+
+  let unmarshal fname = with_open_in_bin fname Marshal.from_channel
+end
+
 include Astring
diff --git a/test/generators/dune b/test/generators/dune
index cb136bfb4b..697a31775b 100644
--- a/test/generators/dune
+++ b/test/generators/dune
@@ -26,7 +26,7 @@
 
 (library
  (name gen_rules_lib)
- (libraries sexplib0 unix fpath)
+ (libraries sexplib0 unix fpath odoc_utils)
  (enabled_if
   (>= %{ocaml_version} 4.04)))
 
diff --git a/test/generators/gen_rules_lib.ml b/test/generators/gen_rules_lib.ml
index 845d818173..8f5a3e7fb8 100644
--- a/test/generators/gen_rules_lib.ml
+++ b/test/generators/gen_rules_lib.ml
@@ -1,3 +1,5 @@
+open Odoc_utils
+
 type sexp = Sexplib0.Sexp.t = Atom of string | List of sexp list
 
 type enabledif = Min of string | Max of string | MinMax of string * string
@@ -102,26 +104,12 @@ let gen_rule_for_source_file { input; cmt; odoc; odocl; enabledif } =
       odocl_target_rule enabledif odoc odocl;
     ]
 
-let read_lines ic =
-  let lines = ref [] in
-  try
-    while true do
-      lines := input_line ic :: !lines
-    done;
-    assert false
-  with End_of_file -> List.rev !lines
-
-let lines_of_file path =
-  let ic = open_in (Fpath.to_string path) in
-  let lines = read_lines ic in
-  close_in ic;
-  lines
-
 let targets_file_path f = Fpath.(base f |> set_ext ".targets")
 
 let expected_targets backend test_case =
   let targets_file = Fpath.( // ) backend (targets_file_path test_case) in
-  try lines_of_file targets_file |> List.map Fpath.v with _ -> []
+  try Io_utils.read_lines (Fpath.to_string targets_file) |> List.map Fpath.v
+  with _ -> []
 
 let gen_targets_file enabledif ?flat_flag backend target_path relinput =
   let flat_flag = match flat_flag with None -> [] | Some x -> [ x ] in
diff --git a/test/odoc_print/occurrences_print.ml b/test/odoc_print/occurrences_print.ml
index b8adaea436..429843cb6e 100644
--- a/test/odoc_print/occurrences_print.ml
+++ b/test/odoc_print/occurrences_print.ml
@@ -1,11 +1,14 @@
+open Odoc_utils
+
 module H = Hashtbl.Make (Odoc_model.Paths.Identifier)
 
 let run inp =
-  let ic = open_in_bin inp in
-  let htbl : Odoc_occurrences.Table.t = Marshal.from_channel ic in
+  let htbl : Odoc_occurrences.Table.t = Io_utils.unmarshal inp in
   Odoc_occurrences.Table.iter
     (fun id { Odoc_occurrences.Table.direct; indirect; _ } ->
-      let id = String.concat "." (Odoc_model.Paths.Identifier.fullname id) in
+      let id =
+        String.concat ~sep:"." (Odoc_model.Paths.Identifier.fullname id)
+      in
       Format.printf "%s was used directly %d times and indirectly %d times\n" id
         direct indirect)
     htbl
diff --git a/test/xref2/lib/common.cppo.ml b/test/xref2/lib/common.cppo.ml
index 33edd92f21..c716cb42f8 100644
--- a/test/xref2/lib/common.cppo.ml
+++ b/test/xref2/lib/common.cppo.ml
@@ -85,36 +85,6 @@ let signature_of_mli_string str =
     let _, sg, _ = model_of_string str in
     sg
 
-let string_of_file f =
-    let ic = open_in f in
-    let buffer = Buffer.create 100 in
-    let rec loop () =
-        try
-            Buffer.add_channel buffer ic 1024;
-            loop ()
-        with End_of_file ->
-            ()
-    in loop ();
-    close_in ic;
-    Buffer.contents buffer
-
-let file_of_string ~filename str =
-    let oc = open_out filename in
-    Printf.fprintf oc "%s%!" str;
-    close_out oc
-
-let list_files path =
-    Sys.readdir path |> Array.to_list
-
-let load_cmti filename =
-  let make_root = root_of_compilation_unit ~package:"nopackage" ~hidden:false in
-  Odoc_loader.read_cmti ~make_root ~filename
-
-let load_cmt filename =
-    let make_root = root_of_compilation_unit ~package:"nopackage" ~hidden:false in
-    Odoc_loader.read_cmt ~make_root ~filename
-  
-
 module Ident = Ident
 
 module LangUtils = struct