diff --git a/src/bin_sig.ml b/src/bin_sig.ml
index ec81353c..6cda3669 100644
--- a/src/bin_sig.ml
+++ b/src/bin_sig.ml
@@ -782,7 +782,8 @@ module ExchangeKeySet = struct
     (* purpose.purpose = TALER_SIGNATURE_EXCHANGE_KEY_SET *)
     type r = {
       list_issue_date: TimestampNBO.t;
-      hc: Hash_64.t;
+      (* hash over a concatenation of master_sigs *)
+      hc: H64.t;
     }
 
     let bin =
@@ -791,7 +792,7 @@ module ExchangeKeySet = struct
       record (fun _purpose list_issue_date hc -> { list_issue_date; hc })
       |+ Purpose.field _purpose
       |+ field TimestampNBO.bin (fun t -> t.list_issue_date)
-      |+ field Hash_64.bin (fun t -> t.hc)
+      |+ field H64.bin (fun t -> t.hc)
       |> sealr
   end
 
diff --git a/src/http_keys.ml b/src/http_keys.ml
index fb58aefe..c5fdfada 100644
--- a/src/http_keys.ml
+++ b/src/http_keys.ml
@@ -182,7 +182,7 @@ let mk_keys ~db_conn (module Sm : Secmod.S) ~last_issue_date =
       |> List.filter_map (fun v -> v.Denom_data.master_sig)
       |> List.map Bin_sig.DenominationKeyValidity.to_octets
       |> String.concat ""
-      |> Hash.Hash_64.hash
+      |> Hash.H64.hash
     in
     let open Bin_sig.ExchangeKeySet in
     sign_f ~f:(Sm.sign_with_signkey ~pub:exchange_pub) R.{ list_issue_date; hc }
diff --git a/tools/offline_impl.ml b/tools/offline_impl.ml
index c0c90632..e56fdbc1 100644
--- a/tools/offline_impl.ml
+++ b/tools/offline_impl.ml
@@ -146,7 +146,7 @@ let enable_auditor ~output ~master_key ~auditor_url ~auditor_name ~auditor_pub
       {
         start_date= validity_start;
         auditor_pub;
-        h_auditor_url= Hash_64_cstr.hash auditor_url;
+        h_auditor_url= Hash.Cstring.H64.hash auditor_url;
       }
   in
   let v =
@@ -177,7 +177,7 @@ let wire_fee ~output ~master_key ~wire_method ~fee_start ~fee_end ~closing_fee
     let open Bin_sig.MasterWireFee in
     sign_f ~f:(EddsaSignature.sign ~key)
       {
-        h_wire_method= Hash_64_cstr.hash wire_method;
+        h_wire_method= Hash.Cstring.H64.hash wire_method;
         start_date= fee_start;
         end_date= fee_end;
         closing_fee;
@@ -210,7 +210,7 @@ let drain ~output ~master_key ~debit_account_section ~credit_payto_uri ~wtid
         wtid;
         date;
         amount;
-        h_section= Hash_64_cstr.hash debit_account_section;
+        h_section= Hash.Cstring.H64.hash debit_account_section;
         h_payto= FullPaytoHash.hash credit_payto_uri;
       }
   in
diff --git a/tools/offline_sig.ml b/tools/offline_sig.ml
index 452d027f..aca4f735 100644
--- a/tools/offline_sig.ml
+++ b/tools/offline_sig.ml
@@ -1,5 +1,4 @@
 open Crypto
-open Hash
 open Api
 
 let verify_future_keys_response =
@@ -22,7 +21,7 @@ let verify_future_keys_response =
     let h_denom_pub =
       DenominationHash.hash (DenominationKey.to_octets denom_pub)
     in
-    let h_section_name = Hash_64_cstr.hash section_name in
+    let h_section_name = Hash.Cstring.H64.hash section_name in
     let anchor_time = stamp_start in
     let duration_withdraw = Timestamp.diff stamp_start stamp_expire_withdraw in
     let open Bin_sig.DenominationKeyAnnouncement in