diff --git a/package.json b/package.json
index 0a47eb8f..99a5fd4a 100644
--- a/package.json
+++ b/package.json
@@ -59,7 +59,8 @@
     "debug": "^4.3.4",
     "pony-cause": "^2.1.10",
     "semver": "^7.5.4",
-    "superstruct": "^1.0.3"
+    "superstruct": "^1.0.3",
+    "uuid": "^9.0.1"
   },
   "devDependencies": {
     "@lavamoat/allow-scripts": "^2.3.1",
@@ -72,6 +73,7 @@
     "@types/jest": "^28.1.7",
     "@types/jest-when": "^3.5.3",
     "@types/node": "^17.0.23",
+    "@types/uuid": "^9.0.8",
     "@typescript-eslint/eslint-plugin": "^5.43.0",
     "@typescript-eslint/parser": "^5.43.0",
     "depcheck": "^1.4.7",
diff --git a/src/fs.test.ts b/src/fs.test.ts
index bfab32ed..cffb5a88 100644
--- a/src/fs.test.ts
+++ b/src/fs.test.ts
@@ -3,6 +3,7 @@ import { when } from 'jest-when';
 import os from 'os';
 import path from 'path';
 import util from 'util';
+import * as uuid from 'uuid';
 
 import {
   createSandbox,
@@ -18,6 +19,16 @@ import {
 
 const { withinSandbox } = createSandbox('utils');
 
+// Clone the `uuid` module so that we can spy on its exports
+jest.mock('uuid', () => {
+  return {
+    // This is how to mock an ES-compatible module in Jest.
+    // eslint-disable-next-line @typescript-eslint/naming-convention
+    __esModule: true,
+    ...jest.requireActual('uuid'),
+  };
+});
+
 describe('fs', () => {
   describe('readFile', () => {
     it('reads the contents of the given file as a UTF-8-encoded string', async () => {
@@ -674,9 +685,14 @@ describe('fs', () => {
     });
 
     it('does not create the sandbox directory immediately', async () => {
+      jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
       createSandbox('utils-fs');
 
-      const sandboxDirectoryPath = path.join(os.tmpdir(), 'utils-fs');
+      const sandboxDirectoryPath = path.join(
+        os.tmpdir(),
+        'utils-fs',
+        'AAAA-AAAA-AAAA-AAAA',
+      );
 
       await expect(fs.promises.stat(sandboxDirectoryPath)).rejects.toThrow(
         'ENOENT',
@@ -686,16 +702,15 @@ describe('fs', () => {
     describe('withinSandbox', () => {
       it('creates the sandbox directory and keeps it around before its given function ends', async () => {
         expect.assertions(1);
-
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
-        const sandboxDirectoryPath = path.join(
-          os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
-        );
 
         await withinTestSandbox(async () => {
+          const sandboxDirectoryPath = path.join(
+            os.tmpdir(),
+            'utils-fs',
+            'AAAA-AAAA-AAAA-AAAA',
+          );
           expect(await fs.promises.stat(sandboxDirectoryPath)).toStrictEqual(
             expect.anything(),
           );
@@ -703,32 +718,32 @@ describe('fs', () => {
       });
 
       it('removes the sandbox directory after its given function ends', async () => {
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
-        const sandboxDirectoryPath = path.join(
-          os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
-        );
 
         await withinTestSandbox(async () => {
           // do nothing
         });
 
+        const sandboxDirectoryPath = path.join(
+          os.tmpdir(),
+          'utils-fs',
+          'AAAA-AAAA-AAAA-AAAA',
+        );
         await expect(fs.promises.stat(sandboxDirectoryPath)).rejects.toThrow(
           'ENOENT',
         );
       });
 
       it('throws if the sandbox directory already exists', async () => {
-        const nowTimestamp = new Date('2023-01-01').getTime();
-        jest.setSystemTime(nowTimestamp);
+        jest.spyOn(uuid, 'v4').mockReturnValue('AAAA-AAAA-AAAA-AAAA');
         const { withinSandbox: withinTestSandbox } = createSandbox('utils-fs');
+
         const sandboxDirectoryPath = path.join(
           os.tmpdir(),
-          `utils-fs--${nowTimestamp}`,
+          'utils-fs',
+          'AAAA-AAAA-AAAA-AAAA',
         );
-
         try {
           await fs.promises.mkdir(sandboxDirectoryPath);
 
diff --git a/src/fs.ts b/src/fs.ts
index 0f6b4ef3..6df5b60e 100644
--- a/src/fs.ts
+++ b/src/fs.ts
@@ -4,6 +4,7 @@
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
+import * as uuid from 'uuid';
 
 import { isErrorWithCode, wrapError } from './errors';
 import type { Json } from './json';
@@ -240,8 +241,7 @@ export async function forceRemove(entryPath: string): Promise<void> {
  * ```
  */
 export function createSandbox(projectName: string): FileSandbox {
-  const timestamp = new Date().getTime();
-  const directoryPath = path.join(os.tmpdir(), `${projectName}--${timestamp}`);
+  const directoryPath = path.join(os.tmpdir(), projectName, uuid.v4());
 
   return {
     directoryPath,
diff --git a/yarn.lock b/yarn.lock
index 2c3c6ca8..93b09137 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1226,6 +1226,7 @@ __metadata:
     "@types/jest": ^28.1.7
     "@types/jest-when": ^3.5.3
     "@types/node": ^17.0.23
+    "@types/uuid": ^9.0.8
     "@typescript-eslint/eslint-plugin": ^5.43.0
     "@typescript-eslint/parser": ^5.43.0
     debug: ^4.3.4
@@ -1253,6 +1254,7 @@ __metadata:
     tsup: ^7.2.0
     typedoc: ^0.23.15
     typescript: ~4.8.4
+    uuid: ^9.0.1
   languageName: unknown
   linkType: soft
 
@@ -1694,6 +1696,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@types/uuid@npm:^9.0.8":
+  version: 9.0.8
+  resolution: "@types/uuid@npm:9.0.8"
+  checksum: b8c60b7ba8250356b5088302583d1704a4e1a13558d143c549c408bf8920535602ffc12394ede77f8a8083511b023704bc66d1345792714002bfa261b17c5275
+  languageName: node
+  linkType: hard
+
 "@types/yargs-parser@npm:*":
   version: 21.0.0
   resolution: "@types/yargs-parser@npm:21.0.0"
@@ -7673,6 +7682,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"uuid@npm:^9.0.1":
+  version: 9.0.1
+  resolution: "uuid@npm:9.0.1"
+  bin:
+    uuid: dist/bin/uuid
+  checksum: 39931f6da74e307f51c0fb463dc2462807531dc80760a9bff1e35af4316131b4fc3203d16da60ae33f07fdca5b56f3f1dd662da0c99fea9aaeab2004780cc5f4
+  languageName: node
+  linkType: hard
+
 "v8-compile-cache-lib@npm:^3.0.1":
   version: 3.0.1
   resolution: "v8-compile-cache-lib@npm:3.0.1"