diff --git a/test/validate_response.ml b/test/validate_response.ml
index fd6072be..0ce0fbc3 100644
--- a/test/validate_response.ml
+++ b/test/validate_response.ml
@@ -64,7 +64,19 @@ let keys content =
         if Signkey.is_valid_at ~timestamp:now sk then Ok ()
         else Fmt.error "exchange_pub is not valid at the current time"
   in
-  (* validate exchange_sig *)
+  let* () =
+    let hc =
+      v.denominations
+      |> List.map (fun (DenomGroup.Rsa g) -> g.RsaDenomGroup.denoms)
+      |> List.concat_map (List.map (fun dn -> dn.RsaDenom.master_sig))
+      |> List.map Signatures.DenominationKeyValidity.to_octets
+      |> String.concat ""
+      |> Hash.H64.hash
+    in
+    let open Signatures.ExchangeKeySet in
+    verify v.exchange_pub v.exchange_sig
+      R.{ list_issue_date= v.list_issue_date; hc }
+  in
 
   (* validate denominations *)
   (* validate global-fees *)