diff --git a/dovecot/keyproxy.go b/dovecot/keyproxy.go
index f1248dcc6596bf94d89c8e0233b43c8c8522ac54..c3c621f374099a6bd32d3c2cdac24a5b5da10747 100644
--- a/dovecot/keyproxy.go
+++ b/dovecot/keyproxy.go
@@ -91,7 +91,7 @@ func (s *KeyLookupProxy) Lookup(ctx context.Context, key string) (interface{}, b
 		return s.lookupUserdb(ctx, key[7:])
 	default:
 		log.Printf("unknown key %s", key)
-		return nil, false
+		return nil, false, nil
 	}
 }