diff --git a/packages/SwingSet/src/controller/controller.js b/packages/SwingSet/src/controller/controller.js
index c3091989814..eace725d4ce 100644
--- a/packages/SwingSet/src/controller/controller.js
+++ b/packages/SwingSet/src/controller/controller.js
@@ -15,6 +15,7 @@ import { initSwingStore } from '@agoric/swing-store';
 
 import { mustMatch, M } from '@endo/patterns';
 import { checkBundle } from '@endo/check-bundle/lite.js';
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 import engineGC from '@agoric/internal/src/lib-nodejs/engine-gc.js';
 import { startSubprocessWorker } from '@agoric/internal/src/lib-nodejs/spawnSubprocessWorker.js';
 import { waitUntilQuiescent } from '@agoric/internal/src/lib-nodejs/waitUntilQuiescent.js';
@@ -263,13 +264,6 @@ export async function makeSwingsetController(
 
   await kernel.start();
 
-  /**
-   * @param {T} x
-   * @returns {T}
-   * @template T
-   */
-  const defensiveCopy = x => JSON.parse(JSON.stringify(x));
-
   /**
    * Validate and install a code bundle.
    *
@@ -304,7 +298,7 @@ export async function makeSwingsetController(
     writeSlogObject,
 
     dump() {
-      return defensiveCopy(kernel.dump());
+      return deepCopyJsonable(kernel.dump());
     },
 
     verboseDebugMode(flag) {
@@ -340,11 +334,11 @@ export async function makeSwingsetController(
     },
 
     getStats() {
-      return defensiveCopy(kernel.getStats());
+      return deepCopyJsonable(kernel.getStats());
     },
 
     getStatus() {
-      return defensiveCopy(kernel.getStatus());
+      return deepCopyJsonable(kernel.getStatus());
     },
 
     getActivityhash() {
diff --git a/packages/SwingSet/src/controller/initializeSwingset.js b/packages/SwingSet/src/controller/initializeSwingset.js
index 3fb6f0a0768..7ecb1f048c3 100644
--- a/packages/SwingSet/src/controller/initializeSwingset.js
+++ b/packages/SwingSet/src/controller/initializeSwingset.js
@@ -3,7 +3,7 @@ import fs from 'fs';
 import path from 'path';
 
 import { assert, b, Fail } from '@endo/errors';
-import { makeTracer } from '@agoric/internal';
+import { deepCopyJsonable, makeTracer } from '@agoric/internal';
 import { mustMatch } from '@agoric/store';
 import bundleSource from '@endo/bundle-source';
 import { resolve as resolveModuleSpecifier } from 'import-meta-resolve';
@@ -323,7 +323,7 @@ export async function initializeSwingset(
   } = runtimeOptions;
 
   // copy config so we can safely mess with it even if it's shared or hardened
-  config = JSON.parse(JSON.stringify(config));
+  config = deepCopyJsonable(config);
   if (!config.bundles) {
     config.bundles = {};
   }
diff --git a/packages/SwingSet/src/devices/bridge/device-bridge.js b/packages/SwingSet/src/devices/bridge/device-bridge.js
index 216bf6556ca..3cdd8710e24 100644
--- a/packages/SwingSet/src/devices/bridge/device-bridge.js
+++ b/packages/SwingSet/src/devices/bridge/device-bridge.js
@@ -1,5 +1,6 @@
 import { Fail } from '@endo/errors';
 import { Far } from '@endo/far';
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 
 function sanitize(data) {
   if (data === undefined) {
@@ -8,7 +9,7 @@ function sanitize(data) {
   if (data instanceof Error) {
     data = data.stack;
   }
-  return JSON.parse(JSON.stringify(data));
+  return deepCopyJsonable(data);
 }
 
 /**
@@ -32,7 +33,7 @@ export function buildRootDeviceNode(tools) {
 
   function inboundCallback(...args) {
     inboundHandler || Fail`inboundHandler not yet registered`;
-    const safeArgs = JSON.parse(JSON.stringify(args));
+    const safeArgs = deepCopyJsonable(args);
     try {
       SO(inboundHandler).inbound(...harden(safeArgs));
     } catch (e) {
diff --git a/packages/SwingSet/test/upgrade/upgrade-replay.test.js b/packages/SwingSet/test/upgrade/upgrade-replay.test.js
index 1cd95fc32d2..1978de10bbf 100644
--- a/packages/SwingSet/test/upgrade/upgrade-replay.test.js
+++ b/packages/SwingSet/test/upgrade/upgrade-replay.test.js
@@ -4,6 +4,7 @@ import { test } from '../../tools/prepare-test-env-ava.js';
 
 import { assert } from '@endo/errors';
 import { kser } from '@agoric/kmarshal';
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 import { initSwingStore } from '@agoric/swing-store';
 import {
   buildKernelBundles,
@@ -16,10 +17,6 @@ function bfile(name) {
   return new URL(name, import.meta.url).pathname;
 }
 
-function copy(data) {
-  return JSON.parse(JSON.stringify(data));
-}
-
 async function run(c, method, args = []) {
   assert(Array.isArray(args));
   const kpid = c.queueToVatRoot('bootstrap', method, args);
@@ -49,7 +46,12 @@ test('replay after upgrade', async t => {
 
   const ss1 = initSwingStore();
   {
-    await initializeSwingset(copy(config), [], ss1.kernelStorage, initOpts);
+    await initializeSwingset(
+      deepCopyJsonable(config),
+      [],
+      ss1.kernelStorage,
+      initOpts,
+    );
     const c1 = await makeSwingsetController(ss1.kernelStorage, {}, runtimeOpts);
     t.teardown(c1.shutdown);
     c1.pinVatRoot('bootstrap');
diff --git a/packages/SwingSet/test/vat-admin/replay.test.js b/packages/SwingSet/test/vat-admin/replay.test.js
index 24cb2dfd24f..61658ad7fc3 100644
--- a/packages/SwingSet/test/vat-admin/replay.test.js
+++ b/packages/SwingSet/test/vat-admin/replay.test.js
@@ -2,14 +2,11 @@
 // eslint-disable-next-line import/order
 import { test } from '../../tools/prepare-test-env-ava.js';
 
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 import { kser } from '@agoric/kmarshal';
 import { initSwingStore } from '@agoric/swing-store';
 import { buildKernelBundles, buildVatController } from '../../src/index.js';
 
-function copy(data) {
-  return JSON.parse(JSON.stringify(data));
-}
-
 test.before(async t => {
   const kernelBundles = await buildKernelBundles();
   t.context.data = { kernelBundles };
@@ -34,7 +31,7 @@ test.serial('replay dynamic vat', async t => {
 
   const ss1 = initSwingStore();
   {
-    const c1 = await buildVatController(copy(config), [], {
+    const c1 = await buildVatController(deepCopyJsonable(config), [], {
       kernelStorage: ss1.kernelStorage,
       kernelBundles: t.context.data.kernelBundles,
     });
@@ -52,7 +49,7 @@ test.serial('replay dynamic vat', async t => {
   const serialized = ss1.debug.serialize();
   const ss2 = initSwingStore(null, { serialized });
   {
-    const c2 = await buildVatController(copy(config), [], {
+    const c2 = await buildVatController(deepCopyJsonable(config), [], {
       kernelStorage: ss2.kernelStorage,
     });
     t.teardown(c2.shutdown);
diff --git a/packages/boot/test/upgrading/upgrade-vats.test.ts b/packages/boot/test/upgrading/upgrade-vats.test.ts
index ed1647e1303..d5a3d22c14f 100644
--- a/packages/boot/test/upgrading/upgrade-vats.test.ts
+++ b/packages/boot/test/upgrading/upgrade-vats.test.ts
@@ -1,7 +1,7 @@
 /* eslint-disable @jessie.js/safe-await-separator -- test */
 import { test } from '@agoric/swingset-vat/tools/prepare-test-env-ava.js';
 
-import { BridgeId } from '@agoric/internal';
+import { BridgeId, deepCopyJsonable } from '@agoric/internal';
 import { buildVatController } from '@agoric/swingset-vat';
 import { makeRunUtils } from '@agoric/swingset-vat/tools/run-utils.js';
 import { Fail } from '@endo/errors';
@@ -434,8 +434,6 @@ test('upgrade vat-priceAuthority', async t => {
   matchRef(t, reincarnatedRegistry.adminFacet, registry.adminFacet);
 });
 
-const dataOnly = obj => JSON.parse(JSON.stringify(obj));
-
 test('upgrade vat-vow', async t => {
   const bundles = {
     vow: {
@@ -483,7 +481,7 @@ test('upgrade vat-vow', async t => {
   };
   await EV(vowRoot).makeLocalPromiseWatchers(localPromises);
   await EV(vowRoot).makeLocalVowWatchers(localVows);
-  t.deepEqual(dataOnly(await EV(vowRoot).getWatcherResults()), {
+  t.deepEqual(deepCopyJsonable(await EV(vowRoot).getWatcherResults()), {
     promiseForever: { status: 'unsettled' },
     promiseFulfilled: { status: 'fulfilled', value: 'hello' },
     promiseRejected: { status: 'rejected', reason: 'goodbye' },
@@ -533,7 +531,7 @@ test('upgrade vat-vow', async t => {
   });
   await EV(fakeVowKit.resolver).reject(upgradeRejection.reason);
   t.timeout(600_000); // t.timeout.clear() not yet available in our ava version
-  t.deepEqual(dataOnly(await EV(vowRoot).getWatcherResults()), {
+  t.deepEqual(deepCopyJsonable(await EV(vowRoot).getWatcherResults()), {
     promiseForever: upgradeRejection,
     promiseFulfilled: { status: 'fulfilled', value: 'hello' },
     promiseRejected: { status: 'rejected', reason: 'goodbye' },
diff --git a/packages/cosmic-swingset/test/run-policy.test.js b/packages/cosmic-swingset/test/run-policy.test.js
index 7a368621b76..e062b48f622 100644
--- a/packages/cosmic-swingset/test/run-policy.test.js
+++ b/packages/cosmic-swingset/test/run-policy.test.js
@@ -2,7 +2,7 @@
 import test from 'ava';
 import { assert, q, Fail } from '@endo/errors';
 import { E } from '@endo/far';
-import { BridgeId, objectMap } from '@agoric/internal';
+import { BridgeId, deepCopyJsonable, objectMap } from '@agoric/internal';
 import { makeFakeStorageKit } from '@agoric/internal/src/storage-test-utils.js';
 import {
   defaultBootstrapMessage,
@@ -26,7 +26,7 @@ import {
  */
 const makeSourceDescriptors = src => {
   const hardened = objectMap(src, sourceSpec => ({ sourceSpec }));
-  return JSON.parse(JSON.stringify(hardened));
+  return deepCopyJsonable(hardened);
 };
 
 /**
diff --git a/packages/cosmic-swingset/tools/test-kit.js b/packages/cosmic-swingset/tools/test-kit.js
index 88018ef591d..ee14da4a4e7 100644
--- a/packages/cosmic-swingset/tools/test-kit.js
+++ b/packages/cosmic-swingset/tools/test-kit.js
@@ -8,6 +8,7 @@ import {
   QueuedActionType,
 } from '@agoric/internal/src/action-types.js';
 import { makeInitMsg } from '@agoric/internal/src/chain-utils.js';
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 import { initSwingStore } from '@agoric/swing-store';
 import { makeSlogSender } from '@agoric/telemetry';
 import { launch } from '../src/launch-chain.js';
@@ -28,9 +29,6 @@ import { makeQueue, makeQueueStorageMock } from '../src/helpers/make-queue.js';
  * @typedef {(input: T) => T} Replacer
  */
 
-/** @type {Replacer<object>} */
-const deepCopyData = obj => JSON.parse(JSON.stringify(obj));
-
 /** @type {Replacer<object>} */
 const stripUndefined = obj =>
   Object.fromEntries(
@@ -62,7 +60,7 @@ export const defaultInitMessage = harden(
   }),
 );
 export const defaultBootstrapMessage = harden({
-  ...deepCopyData(defaultInitMessage),
+  ...deepCopyJsonable(defaultInitMessage),
   blockHeight: 1,
   blockTime: Math.floor(Date.parse('2010-01-01T00:00Z') / 1000),
   isBootstrap: true,
@@ -184,7 +182,7 @@ export const makeCosmicSwingsetTestKit = async (
   await null;
   /** @type {SwingSetConfig} */
   let config = {
-    ...deepCopyData(baseConfig),
+    ...deepCopyJsonable(baseConfig),
     ...configOverrides,
     ...stripUndefined({ defaultManagerType }),
   };
@@ -209,7 +207,7 @@ export const makeCosmicSwingsetTestKit = async (
 
   if (fixupConfig) config = fixupConfig(config);
 
-  let initMessage = deepCopyData(defaultInitMessage);
+  let initMessage = deepCopyJsonable(defaultInitMessage);
   if (fixupInitMessage) initMessage = fixupInitMessage(initMessage);
   initMessage?.type === SwingsetMessageType.AG_COSMOS_INIT ||
     Fail`initMessage must be AG_COSMOS_INIT`;
diff --git a/packages/internal/src/js-utils.js b/packages/internal/src/js-utils.js
index 88bf990bc0d..70cd6d19c4b 100644
--- a/packages/internal/src/js-utils.js
+++ b/packages/internal/src/js-utils.js
@@ -5,6 +5,17 @@
  *   dependent upon a hardened environment.
  */
 
+/**
+ * Deep-copy a value by round-tripping it through JSON (which drops
+ * function/symbol/undefined values and properties that are non-enumerable
+ * and/or symbol-keyed, and rejects bigint values).
+ *
+ * @template T
+ * @param {T} value
+ * @returns {T}
+ */
+export const deepCopyJsonable = value => JSON.parse(JSON.stringify(value));
+
 /**
  * @param {any} value
  * @param {string | undefined} name
diff --git a/packages/internal/test/snapshots/exports.test.js.md b/packages/internal/test/snapshots/exports.test.js.md
index 036ef8a505c..9da2a6a2453 100644
--- a/packages/internal/test/snapshots/exports.test.js.md
+++ b/packages/internal/test/snapshots/exports.test.js.md
@@ -22,6 +22,7 @@ Generated by [AVA](https://avajs.dev).
       'assertAllDefined',
       'bindAllMethods',
       'cast',
+      'deepCopyJsonable',
       'deepMapObject',
       'deeplyFulfilledObject',
       'forever',
diff --git a/packages/internal/test/snapshots/exports.test.js.snap b/packages/internal/test/snapshots/exports.test.js.snap
index b998abae9ce..730293f20f6 100644
Binary files a/packages/internal/test/snapshots/exports.test.js.snap and b/packages/internal/test/snapshots/exports.test.js.snap differ
diff --git a/packages/solo/src/vat-http.js b/packages/solo/src/vat-http.js
index 6f6b2b93653..1f79ca8a29f 100644
--- a/packages/solo/src/vat-http.js
+++ b/packages/solo/src/vat-http.js
@@ -3,6 +3,7 @@ import { E } from '@endo/eventual-send';
 import { makePromiseKit } from '@endo/promise-kit';
 import { Far } from '@endo/marshal';
 
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
 import { makeNotifierKit } from '@agoric/notifier';
 import { makeCache } from '@agoric/cache';
 import { getReplHandler } from '@agoric/vats/src/repl.js';
@@ -82,7 +83,7 @@ export function buildRootObject(vatPowers) {
     D(commandDevice).sendResponse(
       count,
       isException,
-      obj || JSON.parse(JSON.stringify(obj)),
+      obj || deepCopyJsonable(obj),
     );
 
   // Map an URL only to its latest handler.
@@ -186,7 +187,7 @@ export function buildRootObject(vatPowers) {
       // Launder the data, since the command device tends to pass device nodes
       // when there are empty objects, which screw things up for us.
       // Analysis is in https://github.com/Agoric/agoric-sdk/pull/1956
-      const obj = JSON.parse(JSON.stringify(rawObj));
+      const obj = deepCopyJsonable(rawObj);
       console.debug(
         `vat-http.inbound (from browser) ${count}`,
         JSON.stringify(obj, undefined, 2),
diff --git a/packages/wallet/api/src/wallet.js b/packages/wallet/api/src/wallet.js
index b00a28a9245..7efc95ede75 100644
--- a/packages/wallet/api/src/wallet.js
+++ b/packages/wallet/api/src/wallet.js
@@ -9,8 +9,9 @@
  * types.js file.
  */
 import { E } from '@endo/eventual-send';
-import { makeNotifierKit, observeIteration } from '@agoric/notifier';
 import { Far } from '@endo/marshal';
+import { deepCopyJsonable } from '@agoric/internal/src/js-utils.js';
+import { makeNotifierKit, observeIteration } from '@agoric/notifier';
 
 import { makeWalletRoot } from './lib-wallet.js';
 import pubsub from './pubsub.js';
@@ -54,7 +55,7 @@ export function buildRootObject(vatPowers) {
   const offerSubscriptions = new Map();
 
   const httpSend = (obj, channelHandles) =>
-    E(http).send(JSON.parse(JSON.stringify(obj)), channelHandles);
+    E(http).send(deepCopyJsonable(obj), channelHandles);
 
   const pushOfferSubscriptions = (channelHandle, offers) => {
     const subs = offerSubscriptions.get(channelHandle);
diff --git a/packages/wallet/package.json b/packages/wallet/package.json
index 42dc3336f9e..c25d2b53b0b 100644
--- a/packages/wallet/package.json
+++ b/packages/wallet/package.json
@@ -19,6 +19,7 @@
     "build": "exit 0"
   },
   "dependencies": {
+    "@agoric/internal": "^0.3.2",
     "@agoric/wallet-ui": "0.1.3-solo.0",
     "babel-eslint": "^10.0.3",
     "eslint-plugin-eslint-comments": "^3.1.2",