diff --git a/packages/core/src/runtime/rewrite.ts b/packages/core/src/runtime/rewrite.ts
index 6f8004f..0150518 100644
--- a/packages/core/src/runtime/rewrite.ts
+++ b/packages/core/src/runtime/rewrite.ts
@@ -1,9 +1,9 @@
 /// SPDX-License-Identifier: GPL-3.0-or-later
 /// SPDX-FileCopyrightText: Copyright © 2016-2024 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
 
-import { Turn } from "./actor.js";
+import { Turn, Ref } from "./actor.js";
 import { Bytes, Dictionary, DoubleFloat, IdentityMap, is, isEmbedded, Record, Tuple, stringify } from "@preserves/core";
-import type { Assertion, Handle, Ref } from "./actor.js";
+import type { Assertion, Handle } from "./actor.js";
 import type { SturdyValue } from "../transport/sturdy.js";
 
 import {
@@ -200,7 +200,7 @@ export function rmap(... rewrites: [Pattern, Template][]): Caveat {
 
 export function attenuate(ref: Ref, ... a: Caveat[]): Ref {
     if (a.length === 0) return ref;
-    return { ... ref, attenuation: [... (ref.attenuation ?? []), ... a] };
+    return new Ref(ref.relay, ref.target, [... (ref.attenuation ?? []), ... a]);
 }
 
 export function forwarder(ref: Ref): { proxy: Ref, revoker: Ref } {