diff --git a/packages/boot/index.js b/packages/boot/index.js
index f57638b79ff4..f062e6cc6949 100644
--- a/packages/boot/index.js
+++ b/packages/boot/index.js
@@ -1,3 +1,3 @@
 // @ts-check
 // Ambient types
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
diff --git a/packages/deploy-script-support/test/unitTests/test-coreProposalBehavior.js b/packages/deploy-script-support/test/unitTests/test-coreProposalBehavior.js
index e6423f6b0b5d..c616ccdaa22b 100644
--- a/packages/deploy-script-support/test/unitTests/test-coreProposalBehavior.js
+++ b/packages/deploy-script-support/test/unitTests/test-coreProposalBehavior.js
@@ -2,7 +2,7 @@
 import { test } from '@agoric/zoe/tools/prepare-test-env-ava.js';
 
 import { E } from '@endo/far';
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 import {
   makeAgoricNamesAccess,
   runModuleBehaviors,
diff --git a/packages/inter-protocol/test/smartWallet/test-oracle-integration.js b/packages/inter-protocol/test/smartWallet/test-oracle-integration.js
index 7850e7a531a0..d131909378d5 100644
--- a/packages/inter-protocol/test/smartWallet/test-oracle-integration.js
+++ b/packages/inter-protocol/test/smartWallet/test-oracle-integration.js
@@ -1,4 +1,4 @@
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 
 import { test as anyTest } from '@agoric/zoe/tools/prepare-test-env-ava.js';
 
diff --git a/packages/inter-protocol/test/smartWallet/test-psm-integration.js b/packages/inter-protocol/test/smartWallet/test-psm-integration.js
index 9e64eed111e3..f3cc6448c4c3 100644
--- a/packages/inter-protocol/test/smartWallet/test-psm-integration.js
+++ b/packages/inter-protocol/test/smartWallet/test-psm-integration.js
@@ -1,7 +1,7 @@
 import { test as anyTest } from '@agoric/zoe/tools/prepare-test-env-ava.js';
 
 import { AmountMath, makeIssuerKit } from '@agoric/ertp';
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 import { eventLoopIteration } from '@agoric/internal/src/testing-utils.js';
 import { E } from '@endo/far';
 import { NonNullish } from '@agoric/assert';
diff --git a/packages/smart-wallet/test/supports.js b/packages/smart-wallet/test/supports.js
index 6c8e7a8d03ce..05421bf9b600 100644
--- a/packages/smart-wallet/test/supports.js
+++ b/packages/smart-wallet/test/supports.js
@@ -11,7 +11,7 @@ import {
   makeBoard,
 } from '@agoric/vats/src/core/basic-behaviors.js';
 import { setupClientManager } from '@agoric/vats/src/core/chain-behaviors.js';
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 import { buildRootObject as boardRoot } from '@agoric/vats/src/vat-board.js';
 import { buildRootObject as mintsRoot } from '@agoric/vats/src/vat-mints.js';
 import { makeFakeBankKit } from '@agoric/vats/tools/bank-utils.js';
diff --git a/packages/smart-wallet/test/test-startWalletFactory.js b/packages/smart-wallet/test/test-startWalletFactory.js
index f0425b372a17..1327dadf2ffd 100644
--- a/packages/smart-wallet/test/test-startWalletFactory.js
+++ b/packages/smart-wallet/test/test-startWalletFactory.js
@@ -6,7 +6,7 @@ import { E } from '@endo/far';
 import path from 'path';
 import { makeMockTestSpace } from './supports.js';
 
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 
 /** @type {import('ava').TestFn<Awaited<ReturnType<typeof makeTestContext>>>} */
 const test = anyTest;
diff --git a/packages/smart-wallet/test/test-walletFactory.js b/packages/smart-wallet/test/test-walletFactory.js
index 8572580414a7..7ad379d81ad9 100644
--- a/packages/smart-wallet/test/test-walletFactory.js
+++ b/packages/smart-wallet/test/test-walletFactory.js
@@ -11,7 +11,7 @@ import {
   topicPath,
 } from './supports.js';
 
-import '@agoric/vats/src/core/types.js';
+import '@agoric/vats/src/core/types-ambient.js';
 
 /** @type {import('ava').TestFn<Awaited<ReturnType<makeDefaultTestContext>>>} */
 const test = anyTest;
diff --git a/packages/vats/exported.js b/packages/vats/exported.js
index bcc8da58d671..9fe64fe408d0 100644
--- a/packages/vats/exported.js
+++ b/packages/vats/exported.js
@@ -1 +1 @@
-import './src/core/types.js';
+import './src/core/types-ambient.js';
diff --git a/packages/vats/index.js b/packages/vats/index.js
index 82e779cda7a1..f16221b1572c 100644
--- a/packages/vats/index.js
+++ b/packages/vats/index.js
@@ -1,7 +1,7 @@
 // @ts-check
 // Ambient types
 import '@agoric/zoe/exported.js';
-import './src/core/types.js';
+import './src/core/types-ambient.js';
 
 // eslint-disable-next-line import/export -- no named exports
 export * from './src/types.js';
diff --git a/packages/vats/src/bridge.js b/packages/vats/src/bridge.js
index ae21893141e4..a3b82b445e34 100644
--- a/packages/vats/src/bridge.js
+++ b/packages/vats/src/bridge.js
@@ -3,7 +3,7 @@
 import { M } from '@agoric/store';
 import '@agoric/store/exported.js';
 import { E } from '@endo/far';
-import './core/types.js';
+import './core/types-ambient.js';
 
 const { Fail, details: X } = assert;
 
diff --git a/packages/vats/src/core/types.d.ts b/packages/vats/src/core/types-ambient.d.ts
similarity index 98%
rename from packages/vats/src/core/types.d.ts
rename to packages/vats/src/core/types-ambient.d.ts
index 77142ef45fd5..d5792bfcd48c 100644
--- a/packages/vats/src/core/types.d.ts
+++ b/packages/vats/src/core/types-ambient.d.ts
@@ -341,7 +341,7 @@ type ChainBootstrapSpaceT = {
    */
   instancePrivateArgs: Map<Instance, unknown>;
   namesByAddress: import('../types.js').NameHub;
-  namesByAddressAdmin: import('../types').NamesByAddressAdmin;
+  namesByAddressAdmin: import('../types.js').NamesByAddressAdmin;
   pegasusConnections: import('@agoric/vats').NameHubKit;
   pegasusConnectionsAdmin: import('@agoric/vats').NameAdmin;
   priceAuthorityVat: Awaited<PriceAuthorityVat>;
@@ -370,7 +370,7 @@ type ChainBootstrapSpaceT = {
   /** Used only for testing. Should not appear in any production proposals. */
   testFirstAnchorKit: import('../vat-bank.js').AssetIssuerKit<'nat'>;
   walletBridgeManager: import('../types.js').ScopedBridgeManager | undefined;
-  walletFactoryStartResult: import('./startWalletFactory').WalletFactoryStartResult;
+  walletFactoryStartResult: import('./startWalletFactory.js').WalletFactoryStartResult;
   provisionPoolStartResult: unknown;
   vatStore: import('./utils.js').VatStore;
   zoe: ZoeService;
@@ -437,7 +437,7 @@ type RemoteIssuerKit = {
   brand: Brand;
 };
 type AgoricNamesVat = ERef<
-  ReturnType<typeof import('../vat-agoricNames').buildRootObject>
+  ReturnType<typeof import('../vat-agoricNames.js').buildRootObject>
 >;
 type BankVat = ERef<
   ReturnType<typeof import('../vat-bank.js').buildRootObject>
diff --git a/packages/vats/src/core/types.js b/packages/vats/src/core/types-ambient.js
similarity index 100%
rename from packages/vats/src/core/types.js
rename to packages/vats/src/core/types-ambient.js
diff --git a/packages/zoe/exported.js b/packages/zoe/exported.js
index 227a8133b747..03fb20ed65f0 100644
--- a/packages/zoe/exported.js
+++ b/packages/zoe/exported.js
@@ -1,6 +1,6 @@
 // @jessie-check
 
-import './src/contractFacet/types.js';
+import './src/contractFacet/types-ambient.js';
 import './src/zoeService/types.js';
 import './src/contractSupport/types.js';
 import './src/contracts/exported.js';
diff --git a/packages/zoe/src/contractFacet/types.d.ts b/packages/zoe/src/contractFacet/types-ambient.d.ts
similarity index 100%
rename from packages/zoe/src/contractFacet/types.d.ts
rename to packages/zoe/src/contractFacet/types-ambient.d.ts
diff --git a/packages/zoe/src/contractFacet/types.js b/packages/zoe/src/contractFacet/types-ambient.js
similarity index 100%
rename from packages/zoe/src/contractFacet/types.js
rename to packages/zoe/src/contractFacet/types-ambient.js
diff --git a/packages/zoe/src/contractFacet/zcfMint.js b/packages/zoe/src/contractFacet/zcfMint.js
index 1a3a71e0305a..4522559be235 100644
--- a/packages/zoe/src/contractFacet/zcfMint.js
+++ b/packages/zoe/src/contractFacet/zcfMint.js
@@ -10,7 +10,7 @@ import { addToAllocation, subtractFromAllocation } from './allocationMath.js';
 import '../internal-types.js';
 import { ZcfMintI } from '../typeGuards.js';
 import './internal-types.js';
-import './types.js';
+import './types-ambient.js';
 
 const { Fail } = assert;