diff --git a/index.js b/index.js
index ce203bf3..594497c3 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,4 @@
-import path from 'path';
+import path from 'node:path';
 import {ESLint} from 'eslint';
 import globby from 'globby';
 import {isEqual} from 'lodash-es';
@@ -169,7 +169,7 @@ const getFormatter = async name => {
 	return format;
 };
 
-export default {
+const xo = {
 	getFormatter,
 	getErrorResults: ESLint.getErrorResults,
 	outputFixes: async ({results}) => ESLint.outputFixes(results),
@@ -177,3 +177,5 @@ export default {
 	lintText,
 	lintFiles,
 };
+
+export default xo;
diff --git a/lib/open-report.js b/lib/open-report.js
index 6ce16cb6..02870b0e 100644
--- a/lib/open-report.js
+++ b/lib/open-report.js
@@ -1,4 +1,3 @@
-'use strict';
 import openEditor from 'open-editor';
 
 const sortResults = (a, b) => a.errorCount + b.errorCount > 0 ? (a.errorCount - b.errorCount) : (a.warningCount - b.warningCount);
@@ -37,8 +36,10 @@ const getFiles = (report, predicate) => report.results
 	.sort(sortResults)
 	.map(result => resultToFile(result));
 
-export default report => {
+const openReport = report => {
 	const count = report.errorCount > 0 ? 'errorCount' : 'warningCount';
 	const files = getFiles(report, result => result[count] > 0);
 	openEditor(files);
 };
+
+export default openReport;
diff --git a/lib/options-manager.js b/lib/options-manager.js
index 9c87cb76..48336d94 100644
--- a/lib/options-manager.js
+++ b/lib/options-manager.js
@@ -1,6 +1,5 @@
-'use strict';
-import os from 'os';
-import path from 'path';
+import os from 'node:os';
+import path from 'node:path';
 import fsExtra from 'fs-extra';
 import arrify from 'arrify';
 import {mergeWith, groupBy, flow, pick} from 'lodash-es';
@@ -43,7 +42,7 @@ const resolveFrom = (moduleId, fromDirectory = process.cwd()) => resolveModule(m
 resolveFrom.silent = (moduleId, fromDirectory) => {
 	try {
 		return resolveFrom(moduleId, fromDirectory);
-	} catch { }
+	} catch {}
 };
 
 const resolveLocalConfig = name => resolveModule(normalizePackageName(name, 'eslint-config'), import.meta.url);
@@ -92,7 +91,7 @@ const getEmptyXOConfig = () => ({
 const mergeFn = (previousValue, value, key) => {
 	if (Array.isArray(previousValue)) {
 		if (MERGE_OPTIONS_CONCAT.includes(key)) {
-			return previousValue.concat(value);
+			return [...previousValue, ...value];
 		}
 
 		return value;
@@ -186,7 +185,7 @@ const mergeWithFileConfigs = async (files, options, configFiles) => {
 
 	await Promise.all(Object.entries(groupBy(groups.filter(({options}) => Boolean(options.ts)), group => group.options.tsConfigPath || '')).map(
 		([tsConfigPath, groups]) => {
-			const files = [].concat(...groups.map(group => group.files));
+			const files = groups.flatMap(group => group.files);
 			const cachePath = getTsConfigCachePath(files, tsConfigPath);
 
 			for (const group of groups) {
@@ -386,7 +385,7 @@ const buildXOConfig = options => config => {
 
 		// Only apply if the user has the React plugin
 		if (options.cwd && resolveFrom.silent('eslint-plugin-react', options.cwd)) {
-			config.baseConfig.plugins = config.baseConfig.plugins.concat('react');
+			config.baseConfig.plugins.push('react');
 			config.baseConfig.rules['react/jsx-indent-props'] = ['error', spaces];
 			config.baseConfig.rules['react/jsx-indent'] = ['error', spaces];
 		}
@@ -452,10 +451,10 @@ const buildExtendsConfig = options => config => {
 const buildPrettierConfig = (options, prettierConfig) => config => {
 	if (options.prettier) {
 		// The prettier plugin uses Prettier to format the code with `--fix`
-		config.baseConfig.plugins = config.baseConfig.plugins.concat('prettier');
+		config.baseConfig.plugins.push('prettier');
 
 		// The prettier config overrides ESLint stylistic rules that are handled by Prettier
-		config.baseConfig.extends = config.baseConfig.extends.concat('prettier');
+		config.baseConfig.extends.push('prettier');
 
 		// The `prettier/prettier` rule reports errors if the code is not formatted in accordance to Prettier
 		config.baseConfig.rules['prettier/prettier'] = ['error', mergeWithPrettierConfig(options, prettierConfig)];
@@ -464,7 +463,7 @@ const buildPrettierConfig = (options, prettierConfig) => config => {
 		// See https://github.com/prettier/eslint-config-prettier for the list of plugins overrrides
 		for (const [plugin, prettierConfig] of Object.entries(PRETTIER_CONFIG_OVERRIDE)) {
 			if (options.cwd && resolveFrom.silent(plugin, options.cwd)) {
-				config.baseConfig.extends = config.baseConfig.extends.concat(prettierConfig);
+				config.baseConfig.extends.push(prettierConfig);
 			}
 		}
 	}
@@ -505,7 +504,7 @@ const mergeWithPrettierConfig = (options, prettierOptions) => {
 
 const buildTSConfig = options => config => {
 	if (options.ts) {
-		config.baseConfig.extends = config.baseConfig.extends.concat('xo-typescript');
+		config.baseConfig.extends.push('xo-typescript');
 		config.baseConfig.parser = require.resolve('@typescript-eslint/parser');
 		config.baseConfig.parserOptions = {
 			...config.baseConfig.parserOptions,
@@ -532,7 +531,7 @@ const applyOverrides = (file, options) => {
 
 		const {applicable, hash} = findApplicableOverrides(path.relative(options.cwd, file), overrides);
 
-		options = mergeWith(...[getEmptyXOConfig(), options].concat(applicable.map(override => normalizeOptions(override)), mergeFn));
+		options = mergeWith(getEmptyXOConfig(), options, ...applicable.map(override => normalizeOptions(override)), mergeFn);
 		delete options.files;
 		return {options, hash};
 	}
diff --git a/package.json b/package.json
index 8727be27..9ac6171a 100644
--- a/package.json
+++ b/package.json
@@ -109,10 +109,15 @@
 		"webpack": "^5.41.1"
 	},
 	"eslintConfig": {
-		"extends": "eslint-config-xo"
+		"extends": [
+			"eslint-config-xo",
+			"./config/plugins.cjs",
+			"./config/overrides.cjs"
+		]
 	},
 	"eslintIgnore": [
-		"test/fixtures"
+		"test/fixtures",
+		"coverage"
 	],
 	"ava": {
 		"timeout": "1m"
diff --git a/test/cli.js b/test/cli.js
index cfee0a66..2a75fdc8 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -1,5 +1,5 @@
-import fs from 'fs';
-import path from 'path';
+import fs from 'node:fs';
+import path from 'node:path';
 import test from 'ava';
 import execa from 'execa';
 import slash from 'slash';
diff --git a/test/lint-files.js b/test/lint-files.js
index 4cceaf48..575b834a 100644
--- a/test/lint-files.js
+++ b/test/lint-files.js
@@ -1,4 +1,4 @@
-import path from 'path';
+import path from 'node:path';
 import test from 'ava';
 import createEsmUtils from 'esm-utils';
 import xo from '../index.js';
@@ -200,6 +200,7 @@ test('typescript files', async t => {
 
 test('typescript 2 space option', async t => {
 	const {errorCount, results} = await xo.lintFiles('two-spaces.tsx', {cwd: 'fixtures/typescript', space: 2});
+	// eslint-disable-next-line ava/assertion-arguments
 	t.is(errorCount, 0, JSON.stringify(results[0].messages));
 });
 
@@ -222,6 +223,7 @@ test('webpack import resolver is used if webpack.config.js is found', async t =>
 		},
 	});
 
+	// eslint-disable-next-line ava/assertion-arguments
 	t.is(results[0].errorCount, 1, JSON.stringify(results[0].messages));
 
 	const errorMessage = results[0].messages[0].message;
@@ -247,6 +249,7 @@ test('webpack import resolver config can be passed through webpack option', asyn
 		},
 	});
 
+	// eslint-disable-next-line ava/assertion-arguments
 	t.is(results[0].errorCount, 1, JSON.stringify(results[0].messages));
 });
 
@@ -262,6 +265,7 @@ test('webpack import resolver is used if {webpack: true}', async t => {
 		},
 	});
 
+	// eslint-disable-next-line ava/assertion-arguments
 	t.is(results[0].errorCount, 0, JSON.stringify(results[0]));
 });
 
diff --git a/test/lint-text.js b/test/lint-text.js
index 615afb85..109012ac 100644
--- a/test/lint-text.js
+++ b/test/lint-text.js
@@ -1,5 +1,5 @@
-import {promises as fs} from 'fs';
-import path from 'path';
+import {promises as fs} from 'node:fs';
+import path from 'node:path';
 import test from 'ava';
 import createEsmUtils from 'esm-utils';
 import xo from '../index.js';
diff --git a/test/open-report.js b/test/open-report.js
index 02c57a2d..ad1bb055 100644
--- a/test/open-report.js
+++ b/test/open-report.js
@@ -1,4 +1,5 @@
-import path from 'path';
+/* eslint-disable ava/no-skip-test */
+import path from 'node:path';
 import test from 'ava';
 import proxyquire from 'proxyquire';
 import createEsmUtils from 'esm-utils';
@@ -13,7 +14,7 @@ test.skip('opens nothing when there are no errors nor warnings', async t => {
 
 	const openReport = proxyquire('../lib/open-report', {
 		'open-editor': files => {
-			if (files.length !== 0) {
+			if (files.length > 0) {
 				t.fail();
 			}
 		},
diff --git a/test/options-manager.js b/test/options-manager.js
index f8e38ddf..74245954 100644
--- a/test/options-manager.js
+++ b/test/options-manager.js
@@ -1,4 +1,4 @@
-import path from 'path';
+import path from 'node:path';
 import test from 'ava';
 import {omit} from 'lodash-es';
 import fsExtra from 'fs-extra';
@@ -429,7 +429,7 @@ test('buildConfig: extends', t => {
 test('buildConfig: typescript', t => {
 	const config = manager.buildConfig({ts: true, tsConfigPath: './tsconfig.json'});
 
-	t.deepEqual(config.baseConfig.extends[config.baseConfig.extends.length - 1], 'xo-typescript');
+	t.is(config.baseConfig.extends[config.baseConfig.extends.length - 1], 'xo-typescript');
 	t.is(config.baseConfig.parser, require.resolve('@typescript-eslint/parser'));
 	t.deepEqual(config.baseConfig.parserOptions, {
 		warnOnUnsupportedTypeScriptVersion: false,
diff --git a/test/print-config.js b/test/print-config.js
index e12bc2c7..274db42f 100644
--- a/test/print-config.js
+++ b/test/print-config.js
@@ -1,4 +1,4 @@
-import path from 'path';
+import path from 'node:path';
 import test from 'ava';
 import execa from 'execa';
 import tempWrite from 'temp-write';