diff --git a/lib/oca_lib.ml b/lib/oca_lib.ml
index be79872..1890065 100644
--- a/lib/oca_lib.ml
+++ b/lib/oca_lib.ml
@@ -133,7 +133,7 @@ let mkdir_p dir =
 
 let rec rm_rf dirname =
   let%lwt dir = Lwt_unix.opendir (Fpath.to_string dirname) in
-  Lwt.finalize begin fun () ->
+  begin
     let rec rm_files () =
       match%lwt Lwt_unix.readdir dir with
       | "." | ".." -> rm_files ()
@@ -149,10 +149,11 @@ let rec rm_rf dirname =
           rm_files ()
     in
     try%lwt rm_files () with End_of_file -> Lwt.return_unit
-  end begin fun () ->
+  end
+  [%lwt.finally
     let%lwt () = Lwt_unix.closedir dir in
     Lwt_unix.rmdir (Fpath.to_string dirname)
-  end
+  ]
 
 type timer = float ref
 
diff --git a/server/backend/check.ml b/server/backend/check.ml
index 32cc8ae..229358b 100644
--- a/server/backend/check.ml
+++ b/server/backend/check.ml
@@ -75,11 +75,7 @@ let ocluster_build ~cap ~conf ~base_obuilder ~stdout ~stderr c =
 
 let exec_out ~fexec ~fout =
   let stdin, stdout = Lwt_io.pipe () in
-  let proc =
-    Lwt.finalize
-      (fun () -> fexec ~stdout)
-      (fun () -> Lwt_io.close stdout)
-  in
+  let proc = (fexec ~stdout) [%lwt.finally Lwt_io.close stdout] in
   let%lwt res = fout ~stdin in
   let%lwt () = Lwt_io.close stdin in
   let%lwt r = proc in