diff --git a/src/http_info.ml b/src/http_info.ml
index e2f5ee73..9ddce7a5 100644
--- a/src/http_info.ml
+++ b/src/http_info.ml
@@ -73,22 +73,23 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
   let denom_l =
     (* if `?last_issue_date` query param does not exactly match the `stamp_start`
        of one of the denomination keys, all keys are returned *)
-    match last_issue_date with
-    | None -> denom_l
-    | Some last_issue_date -> (
-        match
-          List.find_opt
+    let stamp_start_opt =
+      match last_issue_date with
+      | None -> None
+      | Some timestamp ->
+          List.find_map
             (fun v ->
-              Timestamp.compare v.Denomination.stamp_start last_issue_date = 0)
+              if Timestamp.compare v.Denomination.stamp_start timestamp = 0 then
+                Some v.stamp_start
+              else None)
             denom_l
-        with
-        | None -> denom_l
-        | Some _ ->
-            List.filter
-              (fun v ->
-                Timestamp.compare v.Denomination.stamp_start last_issue_date
-                >= 0)
-              denom_l)
+    in
+    match stamp_start_opt with
+    | None -> denom_l
+    | Some timestamp ->
+        List.filter
+          (fun v -> Timestamp.compare v.Denomination.stamp_start timestamp >= 0)
+          denom_l
   in
   let* denominations = Denomination.make_denom_group denom_l in
 
@@ -108,9 +109,8 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
     | sk :: _ -> sk.SignKey.key
   in
   let exchange_sig =
-    (* Compact EdDSA signature (binary-only) over the
-       contatentation of all of the master_sigs (in reverse
-       chronological order by group) in the arrays under "denominations". *)
+    (* Compact eddsa signature over the contatentation of all of the master_sigs
+       (in reverse chronological order by group) in the arrays under "denominations" *)
     let hc =
       denom_l
       |> List.map (fun dn -> dn.Denomination.master_sig)