diff --git a/src/exchange/taler-exchange-httpd_refreshes_reveal.c b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
index b1903032e..f9330ebe9 100644
--- a/src/exchange/taler-exchange-httpd_refreshes_reveal.c
+++ b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
@@ -381,7 +381,7 @@ resolve_refreshes_reveal_denominations (struct MHD_Connection *connection,
   {
     struct TALER_EXCHANGEDB_RefreshRevealedCoin *rrc = &rrcs[i];
     struct GNUNET_JSON_Specification spec[] = {
-      TALER_JSON_spec_blinded_planchet ("bp",
+      TALER_JSON_spec_blinded_planchet (NULL,
                                         &rrc->blinded_planchet),
       GNUNET_JSON_spec_end ()
     };