diff --git a/src/pg.ml b/src/pg.ml
index 7ff7a010..678a4cdc 100644
--- a/src/pg.ml
+++ b/src/pg.ml
@@ -55,10 +55,9 @@ let find_signkey =
 let get_active_signkeys =
   let get_active_signkeys =
     Caqti_type.(time ->* signkey_data)
-      "SELECT exchange_pub, valid_from, expire_sign, expire_legal, \
-       exchange_sign_keys.master_sig, signkey_revocations.master_sig FROM \
-       exchange_sign_keys esk WHERE expire_sign > $1 AND NOT EXISTS (SELECT \
-       esk_serial FROM signkey_revocations skr WHERE esk.esk_serial = \
+      "SELECT exchange_pub, valid_from, expire_sign, expire_legal, master_sig, \
+       NULL FROM exchange_sign_keys esk WHERE expire_sign > $1 AND NOT EXISTS \
+       (SELECT esk_serial FROM signkey_revocations skr WHERE esk.esk_serial = \
        skr.esk_serial)"
   in
   fun (module Conn : CONN) ->