diff --git a/package.json b/package.json
index 8314290..2d8a2ff 100644
--- a/package.json
+++ b/package.json
@@ -2,13 +2,14 @@
   "name": "kdljs",
   "version": "0.2.0",
   "description": "KDL parser and serializer.",
+  "type": "module",
   "main": "src/index.js",
   "types": "index.d.ts",
   "scripts": {
     "lint": "standard",
     "test": "mocha --throw-deprecation test/spec.js",
     "changelog": "conventional-changelog -p angular -i CHANGELOG.md -s -r 0 && git add CHANGELOG.md",
-    "docs": "jsdoc -c .jsdoc.js",
+    "docs": "jsdoc -c .jsdoc.cjs",
     "preversion": "npm run lint && npm test",
     "version": "npm run changelog"
   },
diff --git a/src/formatter.js b/src/formatter.js
index f5b4f61..5a029d1 100644
--- a/src/formatter.js
+++ b/src/formatter.js
@@ -3,8 +3,9 @@
  * @memberof module:kdljs
  */
 
-const { validateDocument } = require('./validator.js')
-const { Identifier } = require('./parser/tokens.js')
+import { validateDocument } from './validator.js'
+import { Identifier } from './parser/tokens.js'
+import { bannedIdentifiers } from './parser/base.js'
 
 /* eslint-disable no-control-regex */
 const linespace = /^[\r\n\u0085\u000C\u2028\u2029]$/
@@ -22,14 +23,6 @@ const commonEscapes = {
 }
 
 const identifierPattern = new RegExp('^(' + Identifier.PATTERN.source + ')$')
-const bannedIdentifiers = new Set([
-  'true',
-  'false',
-  'null',
-  'inf',
-  '-inf',
-  'nan'
-])
 
 /**
  * @access private
@@ -293,7 +286,7 @@ function processOptions (options) {
  * @param {module:kdljs.formatter.Options} [options={}] - Formatting options
  * @return {string} formatted KDL file
  */
-module.exports.format = function format (doc, options) {
+export function format (doc, options) {
   if (!validateDocument(doc)) {
     throw new TypeError('Invalid KDL document')
   }
diff --git a/src/index.js b/src/index.js
index 7afda1c..b176876 100644
--- a/src/index.js
+++ b/src/index.js
@@ -6,10 +6,10 @@
  * @borrows module:kdljs.validator.validateDocument as validateDocument
  */
 
-const { parse } = require('./parser/index.js')
-const { format } = require('./formatter.js')
-const { query } = require('./queryEngine.js')
-const { validateDocument } = require('./validator.js')
+import { parse } from './parser/index.js'
+import { format } from './formatter.js'
+import { query } from './queryEngine.js'
+import { validateDocument } from './validator.js'
 
 /**
  * A {@link https://github.com/kdl-org/kdl/blob/main/SPEC.md#document|Document}.
@@ -53,7 +53,9 @@ const { validateDocument } = require('./validator.js')
  * @type {string}
  */
 
-module.exports.parse = parse
-module.exports.format = format
-module.exports.query = query
-module.exports.validateDocument = validateDocument
+export {
+  parse,
+  format,
+  query,
+  validateDocument
+}
diff --git a/src/parser/base.js b/src/parser/base.js
index ead22b1..c56aff7 100644
--- a/src/parser/base.js
+++ b/src/parser/base.js
@@ -3,8 +3,8 @@
  * @memberof module:kdljs.parser
  */
 
-const { EmbeddedActionsParser, createTokenInstance, MismatchedTokenException } = require('chevrotain')
-const Tokens = require('./tokens.js')
+import { EmbeddedActionsParser, createTokenInstance, MismatchedTokenException } from 'chevrotain'
+import * as Tokens from './tokens.js'
 
 /**
  * @type Object<string, string>
@@ -471,6 +471,9 @@ class BaseParser extends EmbeddedActionsParser {
   }
 }
 
-module.exports.escapes = escapes
-module.exports.radix = radix
-module.exports.BaseParser = BaseParser
+export {
+  escapes,
+  radix,
+  bannedIdentifiers,
+  BaseParser
+}
diff --git a/src/parser/index.js b/src/parser/index.js
index c475e28..4ac0af4 100644
--- a/src/parser/index.js
+++ b/src/parser/index.js
@@ -4,7 +4,7 @@
  * @borrows module:kdljs.parser.kdl.parse as parse
  */
 
-const kdl = require('./kdl')
+import * as kdl from './kdl.js'
 
-module.exports.parse = kdl.parse
-module.exports.kdl = kdl
+export const parse = kdl.parse
+export { kdl }
diff --git a/src/parser/kdl.js b/src/parser/kdl.js
index 26db889..7258a35 100644
--- a/src/parser/kdl.js
+++ b/src/parser/kdl.js
@@ -3,9 +3,9 @@
  * @memberof module:kdljs.parser
  */
 
-const { Lexer, MismatchedTokenException, createTokenInstance } = require('chevrotain')
-const { BaseParser } = require('./base.js')
-const Tokens = require('./tokens.js')
+import { Lexer, MismatchedTokenException, createTokenInstance } from 'chevrotain'
+import { BaseParser } from './base.js'
+import * as Tokens from './tokens.js'
 
 const tokens = {
   defaultMode: 'main',
@@ -341,7 +341,7 @@ const parser = new KdlParser()
  * @param {string} text - Input KDL file (or fragment)
  * @return {module:kdljs.parser.kdl.ParseResult} Output
  */
-module.exports.parse = function parse (text) {
+export function parse (text) {
   const { tokens, errors } = lexer.tokenize(text)
 
   if (errors.length) {
@@ -360,6 +360,8 @@ module.exports.parse = function parse (text) {
   }
 }
 
-module.exports.lexer = lexer
-module.exports.parser = parser
-module.exports.KdlParser = KdlParser
+export {
+  lexer,
+  parser,
+  KdlParser
+}
diff --git a/src/parser/kql.js b/src/parser/kql.js
index 936d588..7c35681 100644
--- a/src/parser/kql.js
+++ b/src/parser/kql.js
@@ -3,9 +3,9 @@
  * @memberof module:kdljs.parser
  */
 
-const { Lexer } = require('chevrotain')
-const { BaseParser } = require('./base.js')
-const Tokens = require('./tokens.js')
+import { Lexer } from 'chevrotain'
+import { BaseParser } from './base.js'
+import * as Tokens from './tokens.js'
 
 const tokens = {
   defaultMode: 'main',
@@ -361,7 +361,7 @@ const parser = new KqlParser()
  * @param {string} text - Input KQL file (or fragment)
  * @return {module:kdljs.parser.kql.ParseResult} Output
  */
-module.exports.parse = function parse (text) {
+export function parse (text) {
   parser.input = lexer.tokenize(text).tokens
   const output = parser.query()
 
@@ -371,6 +371,8 @@ module.exports.parse = function parse (text) {
   }
 }
 
-module.exports.lexer = lexer
-module.exports.parser = parser
-module.exports.KqlParser = KqlParser
+export {
+  lexer,
+  parser,
+  KqlParser
+}
diff --git a/src/parser/tokens.js b/src/parser/tokens.js
index 201563e..ac75974 100644
--- a/src/parser/tokens.js
+++ b/src/parser/tokens.js
@@ -1,4 +1,4 @@
-const { createToken, EOF } = require('chevrotain')
+import { createToken, EOF } from 'chevrotain'
 
 // Whitespace and comments
 const WhiteSpace = createToken({
@@ -121,7 +121,7 @@ const PropAccessor = createToken({ name: 'PropAccessor', pattern: /prop\(/ })
 const Accessor = createToken({ name: 'Accessor', pattern: /(name|tag|values|props)\(/ })
 const Comma = createToken({ name: 'Comma', pattern: /,/ })
 
-module.exports = {
+export {
   WhiteSpace,
   BOM,
   NewLine,
diff --git a/src/queryEngine.js b/src/queryEngine.js
index 9d90543..d71b262 100644
--- a/src/queryEngine.js
+++ b/src/queryEngine.js
@@ -3,8 +3,8 @@
  * @memberof module:kdljs
  */
 
-const { parse } = require('./parser/kql.js')
-const { validateDocument } = require('./validator.js')
+import { parse } from './parser/kql.js'
+import { validateDocument } from './validator.js'
 
 /**
  * @typedef Query
@@ -285,7 +285,7 @@ function applyQuery (query, doc) {
  * @param {module:kdljs~QueryString} queryString - Query for selecting and/or transforming results
  * @return {any}
  */
-function query (doc, queryString) {
+export function query (doc, queryString) {
   if (!validateDocument(doc)) {
     throw new TypeError('Invalid KDL document')
   }
@@ -297,5 +297,3 @@ function query (doc, queryString) {
 
   return applyQuery(output, doc)
 }
-
-module.exports.query = query
diff --git a/src/validator.js b/src/validator.js
index 80d50ad..4624e13 100644
--- a/src/validator.js
+++ b/src/validator.js
@@ -8,7 +8,7 @@
  * @param {module:kdljs~Document} doc - KDL document
  * @return {boolean}
  */
-function validateDocument (doc) {
+export function validateDocument (doc) {
   return Array.isArray(doc) && doc.every(node => validateNode(node))
 }
 
@@ -85,5 +85,3 @@ function validateValue (value) {
   const type = typeof value
   return type === 'string' || type === 'number' || type === 'boolean' || value === null
 }
-
-module.exports.validateDocument = validateDocument
diff --git a/test/spec.js b/test/spec.js
index d3d82df..17176bf 100644
--- a/test/spec.js
+++ b/test/spec.js
@@ -1,10 +1,10 @@
 /* eslint-env mocha */
 
-const assert = require('assert')
-const path = require('path')
-const fs = require('fs')
-const suite = require('./suite.json')
-const { parse, format } = require('../')
+import assert from 'node:assert'
+import path from 'node:path'
+import url from 'node:url'
+import fs from 'node:fs'
+import { parse, format } from '../src/index.js'
 
 function prepareExpectations (nodes) {
   return nodes.map(node => ({
@@ -20,6 +20,8 @@ function prepareExpectations (nodes) {
   }))
 }
 
+const __dirname = path.dirname(url.fileURLToPath(import.meta.url))
+const suite = JSON.parse(fs.readFileSync(path.join(__dirname, 'suite.json'), 'utf8'))
 const customTests = path.join(__dirname, './kdl')
 const customTestFile = fs.readdirSync(customTests)