diff --git a/src/management.ml b/src/management.ml
index d1ebb3ad..f4436548 100644
--- a/src/management.ml
+++ b/src/management.ml
@@ -179,6 +179,42 @@ let update_master_signatures ~db_conn ~sm_signkey ~sm_denom
         (h_denom_pub, master_sig))
     |> Secmod_denom.add_master_signatures db_conn sm_denom
   in
+  let* () =
+    (* TODO move to test *)
+    Secmod_denom.get_denoms sm_denom
+    |> list_iter (fun denom ->
+        let error = Error "update_master_signatures sanity check failure" in
+        let* opt =
+          Pg.lookup_denomination_key db_conn denom.Denomination.h_pub
+          |> unwrap_err_caqti
+        in
+        let* ( valid_from,
+               _expire_withdraw,
+               _expire_deposit,
+               _expire_legal,
+               coin,
+               _fee_withdraw,
+               _fee_deposit,
+               _fee_refresh,
+               fee_refund,
+               age_mask ) =
+          match opt with None -> error | Some v -> Ok v
+        in
+        let check = function false -> error | true -> Ok () in
+        (* TODO time *)
+        let timestamp_equal a b =
+          let timestamp_to_int64 = function
+            | None -> None
+            | Some v -> v |> Ptime.to_float_s |> Int64.of_float |> Option.some
+          in
+          timestamp_to_int64 a = timestamp_to_int64 b
+        in
+        let* () = check (timestamp_equal valid_from denom.stamp_start) in
+        let* () = check (coin = denom.value) in
+        let* () = check (fee_refund = denom.fee_refund) in
+        let* () = check (age_mask = denom.age_mask) in
+        Ok ())
+  in
   Ok ()
 
 (* --- *)
@@ -200,7 +236,10 @@ let respond_with_ok_json content req =
 
 let respond_with_res res req =
   match res with
-  | Error err -> respond_with_plain_text_error err req
+  | Error err ->
+      Logs.err (fun m -> m "%s." err);
+      let err = Fmt.str "%s@." err in
+      respond_with_plain_text_error err req
   | Ok content -> respond_with_ok_json content req
 
 let keys_get req server _env =
diff --git a/src/pg.ml b/src/pg.ml
index feda504c..86225798 100644
--- a/src/pg.ml
+++ b/src/pg.ml
@@ -1,10 +1,13 @@
+(* TODO
+   how to fix postgres/caqti tuple type?
+   try something with OID?
+   need to add boilerplate in each query for amounts *)
+
 open Crypto
 
 module Caqti_type = struct
   include Caqti_type
 
-  (* TODO add a dune stanza like for prelude:
-     "(flags (:standard -open Prelude))" *)
   (* we want to use int64 timestamps,
      not postgresql built-in timestamp type *)
   let ptime : Ptime.t option t = Timestamp.caqti
@@ -110,8 +113,10 @@ let lookup_denomination_key =
     Caqti_type.(
       denomination_hash
       ->? t10 time time time time amount amount amount amount amount age_mask)
-      "SELECT valid_from, expire_withdraw, expire_deposit, expire_legal, coin, \
-       fee_withdraw, fee_deposit, fee_refresh, fee_refund, age_mask FROM \
+      "SELECT valid_from, expire_withdraw, expire_deposit, expire_legal, \
+       (coin).val, (coin).frac, (fee_withdraw).val, (fee_withdraw).frac, \
+       (fee_deposit).val, (fee_deposit).frac, (fee_refresh).val, \
+       (fee_refresh).frac, (fee_refund).val, (fee_refund).frac, age_mask FROM \
        denominations WHERE denom_pub_hash=$1"
   in
   fun (module Conn : CONN) (h_denom_pub : DenominationHash.t) ->
diff --git a/src/timestamp.mli b/src/timestamp.mli
index c1ac00ab..ae81b3a3 100644
--- a/src/timestamp.mli
+++ b/src/timestamp.mli
@@ -1,5 +1,6 @@
 (* TODO time
-   not sure about this *)
+   uhuh!
+   need to be int64 for binary/pg round trip *)
 
 type t = Ptime.t option
 type span = Ptime.Span.t option