diff --git a/ocaml/Input_hartree_fock.ml b/ocaml/Input_hartree_fock.ml
index 2444f0a0..bd92e69b 100644
--- a/ocaml/Input_hartree_fock.ml
+++ b/ocaml/Input_hartree_fock.ml
@@ -11,6 +11,7 @@ module Hartree_fock : sig
   val read : unit -> t
   val to_string : t -> string
   val to_rst : t -> Rst_string.t
+  val of_rst : Rst_string.t -> t 
 end = struct
   type t = 
     { n_it_scf_max       : Strictly_positive_int.t;
@@ -71,6 +72,22 @@ SCF convergence criterion (on energy) ::
     |> Rst_string.of_string
   ;;
 
+  let of_rst s =
+    let s = Rst_string.to_string s
+    |> String.split ~on:'\n'
+    |> List.filter ~f:(fun line ->
+        String.contains line '=')
+    |> List.map ~f:(fun line ->
+        "("^(
+        String.tr line ~target:'=' ~replacement:' '
+        )^")" )
+    |> String.concat
+    in
+    Sexp.of_string ("("^s^")")
+    |> t_of_sexp
+  ;;
+
+
 end
 
 
diff --git a/ocaml/test_input.ml b/ocaml/test_input.ml
index 40c8a0a7..30b1ed9c 100644
--- a/ocaml/test_input.ml
+++ b/ocaml/test_input.ml
@@ -83,6 +83,13 @@ let test_hf () =
   let b = Input.Hartree_fock.read ()
   in
   print_endline (Input.Hartree_fock.to_string b);
+  let rst = Input.Hartree_fock.to_rst b in
+  let new_b = Input.Hartree_fock.of_rst rst in
+  print_endline (Input.Hartree_fock.to_string b);
+  if (b = new_b) then
+    print_endline "OK"
+  else
+    print_endline "Failed in rst"
 ;;
 
 let test_mo () =
@@ -117,4 +124,4 @@ test_bielec_intergals ();;
 test_electrons();
 *)
 
-test_electrons();
+test_hf();