diff --git a/src/api.ml b/src/api.ml
index 420d9f9c..e1f36ddc 100644
--- a/src/api.ml
+++ b/src/api.ml
@@ -69,14 +69,12 @@ module HashCode : sig
   type t
 
   val hash : string -> t
-  val to_octets : t -> string
+  val to_denomination_hash : t -> Bin_type.DenominationHash.t
   val jsont : t Jsont.t
 end = struct
   type t = B32.t
 
-  (* TODO rm
-     for convertion to DenominationHash *)
-  let to_octets s = s
+  let to_denomination_hash s = Bin_type.DenominationHash.of_octets s
 
   let hash s =
     let open Digestif.SHA512 in
diff --git a/src/management.ml b/src/management.ml
index 4e51d434..2f6d19f4 100644
--- a/src/management.ml
+++ b/src/management.ml
@@ -99,9 +99,7 @@ let mk_future_keys_response ~(sm_signkey : Secmod_signkey.t)
 let verify_denom_signature ~sm_denom DenomSignature.{ h_denom_pub; master_sig }
     =
   let open Syntax in
-  let denom_hash =
-    Bin_type.DenominationHash.of_octets (HashCode.to_octets h_denom_pub)
-  in
+  let denom_hash = HashCode.to_denomination_hash h_denom_pub in
   let* denom =
     Secmod_denom.get_denoms sm_denom
     |> List.find_opt (fun (denom : Denomination.t) -> denom.h_pub = denom_hash)
@@ -172,10 +170,7 @@ let update_master_signatures ~db_conn ~sm_signkey ~sm_denom
   let* () =
     denom_sigs
     |> List.map (fun DenomSignature.{ h_denom_pub; master_sig } ->
-        (* TODO better denomination-hash type *)
-        let h_denom_pub =
-          Bin_type.DenominationHash.of_octets (HashCode.to_octets h_denom_pub)
-        in
+        let h_denom_pub = HashCode.to_denomination_hash h_denom_pub in
         (h_denom_pub, master_sig))
     |> Secmod_denom.add_master_signatures db_conn sm_denom
   in