diff --git a/.eslintrc.json b/.eslintrc.json
index bd51367..9cff826 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -23,6 +23,9 @@
         "bin/*.js"
       ],
       "rules": {
+        // Executable scripts are not expected to have exports
+        "import/no-unused-modules": "off",
+
         // Executable scripts should have a shebang
         "node/shebang": "off"
       }
diff --git a/bin/hub-ci-status.js b/bin/hub-ci-status.js
index 7c811af..987f27f 100755
--- a/bin/hub-ci-status.js
+++ b/bin/hub-ci-status.js
@@ -4,9 +4,7 @@
  * @license MIT
  */
 
-'use strict';
-
-const main = require('../cli.js');
+import main from '../cli.js';
 
 // This file was invoked directly.
 // Note:  Could pass process.exit as callback to force immediate exit.
diff --git a/cli.js b/cli.js
index 180168c..1b09f7b 100644
--- a/cli.js
+++ b/cli.js
@@ -4,16 +4,14 @@
  * @module hub-ci-status/cli.js
  */
 
-'use strict';
-
-const {
+import {
   Command,
   InvalidOptionArgumentError,
   Option,
-} = require('commander');
+} from 'commander';
 
-const hubCiStatus = require('.');
-const getPackageJson = require('./lib/get-package-json.js');
+import getPackageJson from './lib/get-package-json.js';
+import hubCiStatus from './index.js';
 
 // Same --color options as hub(1)
 const colorOptions = ['always', 'never', 'auto'];
@@ -72,7 +70,7 @@ function countOption(optarg, previous) {
  * @returns {!Promise<number>} Promise for exit code.  Only rejected for
  * arguments with invalid type (or args.length < 2).
  */
-async function hubCiStatusMain(args, options) {
+export default async function hubCiStatusMain(args, options) {
   if (!Array.isArray(args) || args.length < 2) {
     throw new TypeError('args must be an Array with at least 2 items');
   }
@@ -169,5 +167,3 @@ async function hubCiStatusMain(args, options) {
     return 1;
   }
 }
-
-module.exports = hubCiStatusMain;
diff --git a/index.js b/index.js
index 0973174..4383eb9 100644
--- a/index.js
+++ b/index.js
@@ -4,16 +4,14 @@
  * @module hub-ci-status
  */
 
-'use strict';
-
-const fetchCiStatus = require('./lib/fetch-ci-status.js');
-const { resolveCommit } = require('./lib/git-utils.js');
-const { getProjectName } = require('./lib/github-utils.js');
-const {
+import fetchCiStatus from './lib/fetch-ci-status.js';
+import { resolveCommit } from './lib/git-utils.js';
+import { getProjectName } from './lib/github-utils.js';
+import {
   fetchCiStatusMockSymbol,
   getProjectNameMockSymbol,
   resolveCommitMockSymbol,
-} = require('./lib/symbols.js');
+} from './lib/symbols.js';
 
 // Use same "severity" as hub(1) for determining state
 // https://github.com/github/hub/blob/v2.14.2/commands/ci_status.go#L60-L69
@@ -164,8 +162,7 @@ function checkRunToStatus(checkRun) {
  * printed.  0 if the status was printed, non-zero if the status could not
  * be determined.
  */
-module.exports =
-async function hubCiStatus(
+export default async function hubCiStatus(
   rev = 'HEAD',
   {
     [fetchCiStatusMockSymbol]: fetchCiStatusMock,
@@ -218,4 +215,4 @@ async function hubCiStatus(
   }
 
   return stateToExitCode(state);
-};
+}
diff --git a/lib/exec-file-out.js b/lib/exec-file-out.js
index afd7b07..ccace06 100644
--- a/lib/exec-file-out.js
+++ b/lib/exec-file-out.js
@@ -3,9 +3,7 @@
  * @license MIT
  */
 
-'use strict';
-
-const { execFile } = require('child_process');
+import { execFile } from 'child_process';
 
 /** Promisified <code>execFile</code> wrapper which only provides access to
  * <code>stdout</code> and fails if <code>stderr</code> is non-empty.
@@ -19,7 +17,7 @@ const { execFile } = require('child_process');
  * non-whitespace characters.
  * @private
  */
-function execFileOut(file, args, options) {
+export default function execFileOut(file, args, options) {
   return new Promise((resolve, reject) => {
     const child = execFile(file, args, options, (err, stdout, stderr) => {
       if (err) {
@@ -47,5 +45,3 @@ function execFileOut(file, args, options) {
     child.stdin.end();
   });
 }
-
-module.exports = execFileOut;
diff --git a/lib/fetch-ci-status.js b/lib/fetch-ci-status.js
index 405786c..dbe7e12 100644
--- a/lib/fetch-ci-status.js
+++ b/lib/fetch-ci-status.js
@@ -3,27 +3,24 @@
  * @license MIT
  */
 
-'use strict';
-
-const { Octokit } = require('@octokit/rest');
-const { Agent: HttpAgent } = require('http');
-const { Agent: HttpsAgent } = require('https');
-const timers = require('timers');
-const { promisify } = require('util');
-
-const getPackageJson = require('./get-package-json.js');
-const retryAsync = require('./retry-async.js');
-const {
+import { Octokit } from '@octokit/rest';
+import { Agent as HttpAgent } from 'http';
+import { Agent as HttpsAgent } from 'https';
+import timers from 'timers';
+import { promisify } from 'util';
+
+import getPackageJson from './get-package-json.js';
+import retryAsync from './retry-async.js';
+import {
   HttpAgentMockSymbol,
   HttpsAgentMockSymbol,
   OctokitMockSymbol,
-} = require('./symbols.js');
+} from './symbols.js';
 
 // TODO [engine:node@>=15]: import { setTimeout } from 'timers/promises';
 const setTimeoutP = promisify(timers.setTimeout);
 
-module.exports =
-async function fetchCiStatus(apiArgs, options = {}) {
+export default async function fetchCiStatus(apiArgs, options = {}) {
   let agent;
   let { octokit } = options;
   if (octokit === undefined) {
@@ -157,4 +154,4 @@ async function fetchCiStatus(apiArgs, options = {}) {
       agent.destroy();
     }
   }
-};
+}
diff --git a/lib/get-package-json.js b/lib/get-package-json.js
index 2dca941..ff2f153 100644
--- a/lib/get-package-json.js
+++ b/lib/get-package-json.js
@@ -7,11 +7,10 @@
 // once JSON modules are supported non-experimentally:
 // https://github.com/nodejs/node/issues/37141
 
-'use strict';
-
-const { readFile } = require('fs').promises;
-const path = require('path');
+// TODO [engine:node@>=14]: Use readFile from 'fs/promises'
+import { promises as fsPromises } from 'fs';
 
+const { readFile } = fsPromises;
 let packageJsonP;
 
 async function readJson(pathOrUrl, options) {
@@ -23,11 +22,10 @@ async function readJson(pathOrUrl, options) {
  *
  * @returns {!Promise<!object>} Parsed content of package.json.
  */
-module.exports =
-function getPackageJson() {
+export default function getPackageJson() {
   if (!packageJsonP) {
-    packageJsonP = readJson(path.join(__dirname, '..', 'package.json'));
+    packageJsonP = readJson(new URL('../package.json', import.meta.url));
   }
 
   return packageJsonP;
-};
+}
diff --git a/lib/git-utils.js b/lib/git-utils.js
index 4dad9ad..4afbb91 100644
--- a/lib/git-utils.js
+++ b/lib/git-utils.js
@@ -3,10 +3,8 @@
  * @license MIT
  */
 
-'use strict';
-
-const { pathToFileURL } = require('url');
-const execFileOut = require('./exec-file-out.js');
+import { pathToFileURL } from 'url';
+import execFileOut from './exec-file-out.js';
 
 /** Is this process running on Windows?
  *
@@ -22,7 +20,6 @@ const configScopes = Object.freeze(Object.assign(Object.create(null), {
   system: 'system',
   worktree: 'worktree',
 }));
-exports.configScopes = configScopes;
 
 function trim(str) {
   return String.prototype.trim.call(str);
@@ -36,13 +33,13 @@ function trim(str) {
  * branch, not in a git repository, or another error occurs.
  * @private
  */
-exports.getBranch = function getBranch(options) {
+export function getBranch(options) {
   return execFileOut('git', ['symbolic-ref', '-q', '--short', 'HEAD'], options)
     .then(trim)
     .catch((err) => {
       throw new Error(`Unable to determine current branch: ${err.message}`);
     });
-};
+}
 
 /** Parse output of `git config --null`.
  *
@@ -92,7 +89,7 @@ function parseConfigOutput(configData) {
  * @throws Error If an error occurs when parsing the git config output.
  * @private
  */
-exports.getConfig = async function getConfig(scope, options) {
+export async function getConfig(scope, options) {
   if (scope !== undefined && scope !== null && !configScopes[scope]) {
     throw new RangeError(`Invalid scope "${scope}"`);
   }
@@ -111,7 +108,7 @@ exports.getConfig = async function getConfig(scope, options) {
     },
   );
   return parseConfigOutput(configData);
-};
+}
 
 /** Is git URL a local path?
  * From url_is_local_not_ssh in connect.c
@@ -121,10 +118,10 @@ exports.getConfig = async function getConfig(scope, options) {
  * local path.
  * @private
  */
-exports.gitUrlIsLocalNotSsh = function gitUrlIsLocalNotSsh(gitUrl) {
+export function gitUrlIsLocalNotSsh(gitUrl) {
   return !/^[^/]*:/.test(gitUrl)
     || (isWindows && /^[A-Za-z]:/.test(gitUrl));
-};
+}
 
 /** Parses a git URL string into a URL object like {@link url.parse} with
  * support for git helpers, git's SCP-like URL syntax, and local file paths.
@@ -135,8 +132,8 @@ exports.gitUrlIsLocalNotSsh = function gitUrlIsLocalNotSsh(gitUrl) {
  * @throws {TypeError} If gitUrl can not be parsed as a URL.
  * @private
  */
-exports.parseGitUrl = function parseGitUrl(gitUrl) {
-  if (exports.gitUrlIsLocalNotSsh(gitUrl)) {
+export function parseGitUrl(gitUrl) {
+  if (gitUrlIsLocalNotSsh(gitUrl)) {
     const fileUrlObj = pathToFileURL(gitUrl);
     fileUrlObj.helper = undefined;
     return fileUrlObj;
@@ -160,7 +157,7 @@ exports.parseGitUrl = function parseGitUrl(gitUrl) {
   const gitUrlObj = new URL(gitUrl);
   gitUrlObj.helper = helper;
   return gitUrlObj;
-};
+}
 
 /** Resolve a named commit to its hash.
  *
@@ -171,7 +168,7 @@ exports.parseGitUrl = function parseGitUrl(gitUrl) {
  * if <code>commitName</code> can not be resolved.
  * @private
  */
-exports.resolveCommit = async function resolveCommit(commitName, options) {
+export async function resolveCommit(commitName, options) {
   try {
     const sha = await execFileOut(
       'git',
@@ -184,4 +181,4 @@ exports.resolveCommit = async function resolveCommit(commitName, options) {
       `Unable to resolve '${commitName}' to a commit hash: ${err.message}`;
     throw err;
   }
-};
+}
diff --git a/lib/github-utils.js b/lib/github-utils.js
index c88dd21..dfc8925 100644
--- a/lib/github-utils.js
+++ b/lib/github-utils.js
@@ -3,11 +3,9 @@
  * @license MIT
  */
 
-'use strict';
+import { debuglog } from 'util';
 
-const { debuglog } = require('util');
-
-const { getBranch, getConfig, parseGitUrl } = require('./git-utils.js');
+import { getBranch, getConfig, parseGitUrl } from './git-utils.js';
 
 const debug = debuglog('hub-ci-status');
 
@@ -119,8 +117,8 @@ async function tryGetBranch(options) {
  * @returns {!Promise<!Array<string>>} Promise for the owner and repo name,
  * as Array elements, or a UnknownProjectError if they can not be determined.
  */
-exports.getProjectName =
-async function getProjectName(options) {
+// eslint-disable-next-line import/prefer-default-export
+export async function getProjectName(options) {
   // Run getBranch() and getConfig() concurrently.
   const [branch, config] = await Promise.all([
     tryGetBranch(options),
@@ -157,4 +155,4 @@ async function getProjectName(options) {
   }
 
   throw new UnknownProjectError();
-};
+}
diff --git a/lib/retry-async.js b/lib/retry-async.js
index 82ad53a..1c6d0f5 100644
--- a/lib/retry-async.js
+++ b/lib/retry-async.js
@@ -3,13 +3,11 @@
  * @license MIT
  */
 
-'use strict';
+import timers from 'timers';
+import { promisify } from 'util';
 
-const timers = require('timers');
-const { promisify } = require('util');
-
-const constant = require('./retry-async/constant.js');
-const exponential = require('./retry-async/exponential.js');
+import constant from './retry-async/constant.js';
+import exponential from './retry-async/exponential.js';
 
 // TODO [engine:node@>=15]: import { setTimeout } from 'timers/promises';
 const setTimeoutP = promisify(timers.setTimeout);
@@ -48,7 +46,8 @@ function defaultShouldRetry(result) {
  * @private
  * @type {RetryAsyncOptions}
  */
-const DEFAULT_OPTIONS = Object.freeze({
+// eslint-disable-next-line import/no-unused-modules
+export const DEFAULT_OPTIONS = Object.freeze({
   maxTotalMs: Infinity,
   minWaitMs: 4000,
   now: Date.now,
@@ -69,8 +68,7 @@ const DEFAULT_OPTIONS = Object.freeze({
  * @returns {!Promise<TReturn>} Promise for return value of last call to
  * operation.
  */
-module.exports =
-async function retryAsync(
+export default async function retryAsync(
   operation,
   {
     maxTotalMs = DEFAULT_OPTIONS.maxTotalMs,
@@ -126,6 +124,4 @@ async function retryAsync(
       waitIterator.return();
     }
   }
-};
-
-module.exports.DEFAULT_OPTIONS = DEFAULT_OPTIONS;
+}
diff --git a/lib/retry-async/constant.js b/lib/retry-async/constant.js
index 47da0e6..82fb3b3 100644
--- a/lib/retry-async/constant.js
+++ b/lib/retry-async/constant.js
@@ -3,8 +3,6 @@
  * @license MIT
  */
 
-'use strict';
-
 function* generateConstant(value, count) {
   for (; count > 0; count -= 1) {
     yield value;
@@ -21,8 +19,7 @@ function* generateConstant(value, count) {
  * @throws {TypeError} If count is not a number.
  * @throws {RangeError} If count is not a positive integer.
  */
-module.exports =
-function constant(value, count = Infinity) {
+export default function constant(value, count = Infinity) {
   if (typeof count !== 'number') {
     throw new TypeError('count must be a number');
   }
@@ -31,4 +28,4 @@ function constant(value, count = Infinity) {
   }
 
   return generateConstant(value, count);
-};
+}
diff --git a/lib/retry-async/exponential.js b/lib/retry-async/exponential.js
index 0e4463c..55bb09a 100644
--- a/lib/retry-async/exponential.js
+++ b/lib/retry-async/exponential.js
@@ -3,8 +3,6 @@
  * @license MIT
  */
 
-'use strict';
-
 function* generateExponential(factor, initial, maxValue, count) {
   let value = Math.min(initial, maxValue);
   for (let i = 0; i < count; i += 1) {
@@ -27,8 +25,7 @@ function* generateExponential(factor, initial, maxValue, count) {
  * @throws {RangeError} If maxValue or count is NaN, count is negative, or
  * count is not an integer (or Infinity).
  */
-module.exports =
-function exponential(
+export default function exponential(
   factor,
   initial = 1,
   maxValue = Infinity,
@@ -54,4 +51,4 @@ function exponential(
   }
 
   return generateExponential(factor, initial, maxValue, count);
-};
+}
diff --git a/lib/symbols.js b/lib/symbols.js
index dfbeb00..b1211cc 100644
--- a/lib/symbols.js
+++ b/lib/symbols.js
@@ -10,34 +10,34 @@
  *
  * @private
  */
-exports.HttpAgentMockSymbol = Symbol('HttpAgent');
+export const HttpAgentMockSymbol = Symbol('HttpAgent');
 
 /** Symbol of mock function used in place of https.Agent for testing.
  *
  * @private
  */
-exports.HttpsAgentMockSymbol = Symbol('HttpsAgent');
+export const HttpsAgentMockSymbol = Symbol('HttpsAgent');
 
 /** Symbol of mock function used in place of Octokit for testing.
  *
  * @private
  */
-exports.OctokitMockSymbol = Symbol('Octokit');
+export const OctokitMockSymbol = Symbol('Octokit');
 
 /** Symbol of mock function used in place of fetchCiStatus for testing.
  *
  * @private
  */
-exports.fetchCiStatusMockSymbol = Symbol('fetchCiStatus');
+export const fetchCiStatusMockSymbol = Symbol('fetchCiStatus');
 
 /** Symbol of mock function used in place of getProjectName for testing.
  *
  * @private
  */
-exports.getProjectNameMockSymbol = Symbol('getProjectName');
+export const getProjectNameMockSymbol = Symbol('getProjectName');
 
 /** Symbol of mock function used in place of resolveCommit for testing.
  *
  * @private
  */
-exports.resolveCommitMockSymbol = Symbol('resolveCommit');
+export const resolveCommitMockSymbol = Symbol('resolveCommit');
diff --git a/package.json b/package.json
index 0c92e0d..9d51221 100644
--- a/package.json
+++ b/package.json
@@ -17,14 +17,13 @@
     "type": "git",
     "url": "https://github.com/kevinoid/hub-ci-status.git"
   },
-  "type": "commonjs",
+  "type": "module",
   "files": [
     "*.js",
     "bin/",
     "lib/",
     "!**/.*"
   ],
-  "main": "index.js",
   "exports": {
     ".": "./index.js",
     "./package.json": "./package.json"
diff --git a/test-lib/api-responses.js b/test-lib/api-responses.js
index 6d8625e..7fd03a1 100644
--- a/test-lib/api-responses.js
+++ b/test-lib/api-responses.js
@@ -5,8 +5,6 @@
  * @license MIT
  */
 
-"use strict";
-
 const octokitResult = {
   "status": 200,
   "url": "https://api.github.com/repos/github/hello-world/commits/master",
@@ -47,8 +45,7 @@ const octokitResult = {
  * check_runs.conclusion "neutral".
  * @returns {!object} Mock API response with given conclusion values.
  */
-exports.makeCheckRuns =
-function makeCheckRuns(...runConclusions) {
+export function makeCheckRuns(...runConclusions) {
   // https://docs.github.com/en/rest/reference/checks#list-check-runs-for-a-git-reference
   const checkRun = {
     "id": 4,
@@ -156,7 +153,7 @@ function makeCheckRuns(...runConclusions) {
       })
     }
   };
-};
+}
 
 /** Creates an Octokit result object for "Get the combined status for a
  * specific reference".
@@ -165,8 +162,7 @@ function makeCheckRuns(...runConclusions) {
  * ("success", "pending", "failure")
  * @returns {!object} Mock API response with given state values.
  */
-exports.makeCombinedStatus =
-function makeCombinedStatus(...statusStates) {
+export function makeCombinedStatus(...statusStates) {
   // https://docs.github.com/rest/reference/repos#get-the-combined-status-for-a-specific-reference
   const statuses = [
     {
@@ -287,4 +283,4 @@ function makeCombinedStatus(...statusStates) {
       "url": "https://api.github.com/repos/octocat/Hello-World/6dcb09b5b57875f334f61aebed695e2e4193db5e/status"
     }
   };
-};
+}
diff --git a/test-lib/git-init.js b/test-lib/git-init.js
index 63a67be..8f7e68e 100644
--- a/test-lib/git-init.js
+++ b/test-lib/git-init.js
@@ -3,11 +3,9 @@
  * @license MIT
  */
 
-'use strict';
+import execFileOut from '../lib/exec-file-out.js';
 
-const execFileOut = require('../lib/exec-file-out.js');
-
-module.exports = async function gitInit(repoPath, defaultBranch) {
+export default async function gitInit(repoPath, defaultBranch) {
   try {
     await execFileOut(
       'git',
@@ -39,4 +37,4 @@ module.exports = async function gitInit(repoPath, defaultBranch) {
     'git',
     ['-C', repoPath, 'config', 'user.email', 'test@example.com'],
   );
-};
+}
diff --git a/test/.eslintrc.json b/test/.eslintrc.json
index 5c0b46e..f0e0010 100644
--- a/test/.eslintrc.json
+++ b/test/.eslintrc.json
@@ -11,6 +11,9 @@
     // Braces around body of it() function is more consistent/readable
     "arrow-body-style": "off",
 
+    // Tests are not expected to have exports
+    "import/no-unused-modules": "off",
+
     // Allow null use in tests
     "unicorn/no-null": "off"
   }
diff --git a/test/cli.js b/test/cli.js
index 630917c..b767900 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -3,14 +3,12 @@
  * @license MIT
  */
 
-'use strict';
+import assert from 'assert';
+import sinon from 'sinon';
+import stream from 'stream';
 
-const assert = require('assert');
-const sinon = require('sinon');
-const stream = require('stream');
-
-const getPackageJson = require('../lib/get-package-json.js');
-const hubCiStatusCmd = require('../cli.js');
+import getPackageJson from '../lib/get-package-json.js';
+import hubCiStatusCmd from '../cli.js';
 
 const { match } = sinon;
 
diff --git a/test/index.js b/test/index.js
index fa688f8..ae7519f 100644
--- a/test/index.js
+++ b/test/index.js
@@ -3,21 +3,21 @@
  * @license MIT
  */
 
-'use strict';
-
-const ansiStyles = require('ansi-styles');
-const assert = require('assert');
-const sinon = require('sinon');
-const { PassThrough } = require('stream');
-
-const hubCiStatus = require('..');
-const { makeCheckRuns, makeCombinedStatus } =
-  require('../test-lib/api-responses.js');
-const {
+import ansiStyles from 'ansi-styles';
+import assert from 'assert';
+import sinon from 'sinon';
+import { PassThrough } from 'stream';
+
+import hubCiStatus from '../index.js';
+import {
+  makeCheckRuns,
+  makeCombinedStatus,
+} from '../test-lib/api-responses.js';
+import {
   fetchCiStatusMockSymbol,
   getProjectNameMockSymbol,
   resolveCommitMockSymbol,
-} = require('../lib/symbols.js');
+} from '../lib/symbols.js';
 
 const { match } = sinon;
 
diff --git a/test/lib/exec-file-out.js b/test/lib/exec-file-out.js
index a772dc5..22f0ab3 100644
--- a/test/lib/exec-file-out.js
+++ b/test/lib/exec-file-out.js
@@ -3,11 +3,9 @@
  * @license MIT
  */
 
-'use strict';
+import assert from 'assert';
 
-const assert = require('assert');
-
-const execFileOut = require('../../lib/exec-file-out.js');
+import execFileOut from '../../lib/exec-file-out.js';
 
 function neverCalled() {
   throw new Error('Should not be called');
diff --git a/test/lib/fetch-ci-status.js b/test/lib/fetch-ci-status.js
index 7f36829..ace4361 100644
--- a/test/lib/fetch-ci-status.js
+++ b/test/lib/fetch-ci-status.js
@@ -3,23 +3,23 @@
  * @license MIT
  */
 
-'use strict';
-
-const FakeTimers = require('@sinonjs/fake-timers');
-const assert = require('assert');
-const sinon = require('sinon');
-const timers = require('timers');
-const { promisify } = require('util');
-
-const fetchCiStatus = require('../../lib/fetch-ci-status.js');
-const getPackageJson = require('../../lib/get-package-json.js');
-const { makeCheckRuns, makeCombinedStatus } =
-  require('../../test-lib/api-responses.js');
-const {
+import FakeTimers from '@sinonjs/fake-timers';
+import assert from 'assert';
+import sinon from 'sinon';
+import timers from 'timers';
+import { promisify } from 'util';
+
+import fetchCiStatus from '../../lib/fetch-ci-status.js';
+import getPackageJson from '../../lib/get-package-json.js';
+import {
+  makeCheckRuns,
+  makeCombinedStatus,
+} from '../../test-lib/api-responses.js';
+import {
   HttpAgentMockSymbol,
   HttpsAgentMockSymbol,
   OctokitMockSymbol,
-} = require('../../lib/symbols.js');
+} from '../../lib/symbols.js';
 
 // TODO [engine:node@>=15]: import { setImmediate } from 'timers/promises';
 const setImmediateP = promisify(timers.setImmediate);
diff --git a/test/lib/git-utils.js b/test/lib/git-utils.js
index 21a2080..99b7f7d 100644
--- a/test/lib/git-utils.js
+++ b/test/lib/git-utils.js
@@ -3,17 +3,15 @@
  * @license MIT
  */
 
-'use strict';
-
-const assert = require('assert');
-const path = require('path');
-const { dir: makeTempDir } = require('tmp-promise');
-const { pathToFileURL } = require('url');
-
-const getPackageJson = require('../../lib/get-package-json.js');
-const gitInit = require('../../test-lib/git-init.js');
-const gitUtils = require('../../lib/git-utils.js');
-const execFileOut = require('../../lib/exec-file-out.js');
+import assert from 'assert';
+import path from 'path';
+import { dir as makeTempDir } from 'tmp-promise';
+import { pathToFileURL } from 'url';
+
+import getPackageJson from '../../lib/get-package-json.js';
+import gitInit from '../../test-lib/git-init.js';
+import * as gitUtils from '../../lib/git-utils.js';
+import execFileOut from '../../lib/exec-file-out.js';
 
 const defaultBranch = 'main';
 const isWindows = /^win/i.test(process.platform);
diff --git a/test/lib/github-utils.js b/test/lib/github-utils.js
index e2a0141..d0ebc68 100644
--- a/test/lib/github-utils.js
+++ b/test/lib/github-utils.js
@@ -9,16 +9,14 @@
  * @license MIT
  */
 
-'use strict';
-
-const assert = require('assert');
-const { dir: makeTempDir } = require('tmp-promise');
-
-const execFileOut = require('../../lib/exec-file-out.js');
-const getPackageJson = require('../../lib/get-package-json.js');
-const gitInit = require('../../test-lib/git-init.js');
-const { getProjectName } = require('../../lib/github-utils.js');
-const { resolveCommit } = require('../../lib/git-utils.js');
+import assert from 'assert';
+import { dir as makeTempDir } from 'tmp-promise';
+
+import execFileOut from '../../lib/exec-file-out.js';
+import getPackageJson from '../../lib/get-package-json.js';
+import gitInit from '../../test-lib/git-init.js';
+import { getProjectName } from '../../lib/github-utils.js';
+import { resolveCommit } from '../../lib/git-utils.js';
 
 const defaultBranch = 'main';
 const isWindows = /^win/i.test(process.platform);
diff --git a/test/lib/retry-async.js b/test/lib/retry-async.js
index 308a57d..b378d4d 100644
--- a/test/lib/retry-async.js
+++ b/test/lib/retry-async.js
@@ -3,15 +3,13 @@
  * @license MIT
  */
 
-'use strict';
+import FakeTimers from '@sinonjs/fake-timers';
+import assert from 'assert';
+import sinon from 'sinon';
+import timers from 'timers';
+import { promisify } from 'util';
 
-const FakeTimers = require('@sinonjs/fake-timers');
-const assert = require('assert');
-const sinon = require('sinon');
-const timers = require('timers');
-const { promisify } = require('util');
-
-const retryAsync = require('../../lib/retry-async.js');
+import retryAsync from '../../lib/retry-async.js';
 
 // TODO [engine:node@>=15]: import { setImmediate } from 'timers/promises';
 const setImmediateP = promisify(timers.setImmediate);
diff --git a/test/lib/retry-async/constant.js b/test/lib/retry-async/constant.js
index cf2eeb5..0e85892 100644
--- a/test/lib/retry-async/constant.js
+++ b/test/lib/retry-async/constant.js
@@ -3,11 +3,9 @@
  * @license MIT
  */
 
-'use strict';
+import assert from 'assert';
 
-const assert = require('assert');
-
-const constant = require('../../../lib/retry-async/constant.js');
+import constant from '../../../lib/retry-async/constant.js';
 
 describe('retryAsync.constant', () => {
   it('returns an iterable of number first argument', () => {
diff --git a/test/lib/retry-async/exponential.js b/test/lib/retry-async/exponential.js
index 40161f9..d2d4087 100644
--- a/test/lib/retry-async/exponential.js
+++ b/test/lib/retry-async/exponential.js
@@ -3,11 +3,9 @@
  * @license MIT
  */
 
-'use strict';
+import assert from 'assert';
 
-const assert = require('assert');
-
-const exponential = require('../../../lib/retry-async/exponential.js');
+import exponential from '../../../lib/retry-async/exponential.js';
 
 describe('retryAsync.exponential', () => {
   it('returns an iterable of count exponentially increasing values', () => {