diff --git a/src/index.ts b/src/index.ts
index 20a078de..78e4d727 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,185 +1,191 @@
-import {readFileSync} from 'fs'
-import {JSONSchema4} from 'json-schema'
-import {Options as $RefOptions} from '@bcherny/json-schema-ref-parser'
-import {cloneDeep, endsWith, merge} from 'lodash'
-import {dirname} from 'path'
-import {Options as PrettierOptions} from 'prettier'
-import {format} from './formatter'
-import {generate} from './generator'
-import {normalize} from './normalizer'
-import {optimize} from './optimizer'
-import {parse} from './parser'
-import {dereference} from './resolver'
-import {error, stripExtension, Try, log} from './utils'
-import {validate} from './validator'
-import {isDeepStrictEqual} from 'util'
-import {link} from './linker'
-import {validateOptions} from './optionValidator'
-
-export {EnumJSONSchema, JSONSchema, NamedEnumJSONSchema, CustomTypeJSONSchema} from './types/JSONSchema'
-
-export interface Options {
-  /**
-   * [$RefParser](https://github.com/BigstickCarpet/json-schema-ref-parser) Options, used when resolving `$ref`s
-   */
-  $refOptions: $RefOptions
-  /**
-   * Default value for additionalProperties, when it is not explicitly set.
-   */
-  additionalProperties: boolean
-  /**
-   * Disclaimer comment prepended to the top of each generated file.
-   */
-  bannerComment: string
-  /**
-   * Root directory for resolving [`$ref`](https://tools.ietf.org/id/draft-pbryan-zyp-json-ref-03.html)s.
-   */
-  cwd: string
-  /**
-   * Declare external schemas referenced via `$ref`?
-   */
-  declareExternallyReferenced: boolean
-  /**
-   * Prepend enums with [`const`](https://www.typescriptlang.org/docs/handbook/enums.html#computed-and-constant-members)?
-   */
-  enableConstEnums: boolean
-  /**
-   * Format code? Set this to `false` to improve performance.
-   */
-  format: boolean
-  /**
-   * Ignore maxItems and minItems for `array` types, preventing tuples being generated.
-   */
-  ignoreMinAndMaxItems: boolean
-  /**
-   * Maximum number of unioned tuples to emit when representing bounded-size array types,
-   * before falling back to emitting unbounded arrays. Increase this to improve precision
-   * of emitted types, decrease it to improve performance, or set it to `-1` to ignore
-   * `minItems` and `maxItems`.
-   */
-  maxItems: number
-  /**
-   * Append all index signatures with `| undefined` so that they are strictly typed.
-   *
-   * This is required to be compatible with `strictNullChecks`.
-   */
-  strictIndexSignatures: boolean
-  /**
-   * A [Prettier](https://prettier.io/docs/en/options.html) configuration.
-   */
-  style: PrettierOptions
-  /**
-   * Generate code for `definitions` that aren't referenced by the schema?
-   */
-  unreachableDefinitions: boolean
-  /**
-   * Generate unknown type instead of any
-   */
-  unknownAny: boolean
-}
-
-export const DEFAULT_OPTIONS: Options = {
-  $refOptions: {},
-  additionalProperties: true, // TODO: default to empty schema (as per spec) instead
-  bannerComment: `/* eslint-disable */
-/**
-* This file was automatically generated by json-schema-to-typescript.
-* DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,
-* and run json-schema-to-typescript to regenerate this file.
-*/`,
-  cwd: process.cwd(),
-  declareExternallyReferenced: true,
-  enableConstEnums: true,
-  format: true,
-  ignoreMinAndMaxItems: false,
-  maxItems: 20,
-  strictIndexSignatures: false,
-  style: {
-    bracketSpacing: false,
-    printWidth: 120,
-    semi: true,
-    singleQuote: false,
-    tabWidth: 2,
-    trailingComma: 'none',
-    useTabs: false,
-  },
-  unreachableDefinitions: false,
-  unknownAny: true,
-}
-
-export function compileFromFile(filename: string, options: Partial<Options> = DEFAULT_OPTIONS): Promise<string> {
-  const contents = Try(
-    () => readFileSync(filename),
-    () => {
-      throw new ReferenceError(`Unable to read file "${filename}"`)
-    },
-  )
-  const schema = Try<JSONSchema4>(
-    () => JSON.parse(contents.toString()),
-    () => {
-      throw new TypeError(`Error parsing JSON in file "${filename}"`)
-    },
-  )
-  return compile(schema, stripExtension(filename), {cwd: dirname(filename), ...options})
-}
-
-export async function compile(schema: JSONSchema4, name: string, options: Partial<Options> = {}): Promise<string> {
-  validateOptions(options)
-
-  const _options = merge({}, DEFAULT_OPTIONS, options)
-
-  const start = Date.now()
-  function time() {
-    return `(${Date.now() - start}ms)`
-  }
-
-  // normalize options
-  if (!endsWith(_options.cwd, '/')) {
-    _options.cwd += '/'
-  }
-
-  // Initial clone to avoid mutating the input
-  const _schema = cloneDeep(schema)
-
-  const {dereferencedPaths, dereferencedSchema} = await dereference(_schema, _options)
-  if (process.env.VERBOSE) {
-    if (isDeepStrictEqual(_schema, dereferencedSchema)) {
-      log('green', 'dereferencer', time(), '✅ No change')
-    } else {
-      log('green', 'dereferencer', time(), '✅ Result:', dereferencedSchema)
-    }
-  }
-
-  const linked = link(dereferencedSchema)
-  if (process.env.VERBOSE) {
-    log('green', 'linker', time(), '✅ No change')
-  }
-
-  const errors = validate(linked, name)
-  if (errors.length) {
-    errors.forEach(_ => error(_))
-    throw new ValidationError()
-  }
-  if (process.env.VERBOSE) {
-    log('green', 'validator', time(), '✅ No change')
-  }
-
-  const normalized = normalize(linked, dereferencedPaths, name, _options)
-  log('yellow', 'normalizer', time(), '✅ Result:', normalized)
-
-  const parsed = parse(normalized, _options)
-  log('blue', 'parser', time(), '✅ Result:', parsed)
-
-  const optimized = optimize(parsed, _options)
-  log('cyan', 'optimizer', time(), '✅ Result:', optimized)
-
-  const generated = generate(optimized, _options)
-  log('magenta', 'generator', time(), '✅ Result:', generated)
-
-  const formatted = format(generated, _options)
-  log('white', 'formatter', time(), '✅ Result:', formatted)
-
-  return formatted
-}
-
-export class ValidationError extends Error {}
+import {readFileSync} from 'fs'
+import {JSONSchema4} from 'json-schema'
+import {Options as $RefOptions} from '@bcherny/json-schema-ref-parser'
+import {cloneDeep, endsWith, merge} from 'lodash'
+import {dirname} from 'path'
+import {Options as PrettierOptions} from 'prettier'
+import {format} from './formatter'
+import {generate} from './generator'
+import {normalize} from './normalizer'
+import {optimize} from './optimizer'
+import {parse} from './parser'
+import {dereference} from './resolver'
+import {error, stripExtension, Try, log} from './utils'
+import {validate} from './validator'
+import {isDeepStrictEqual} from 'util'
+import {link} from './linker'
+import {validateOptions} from './optionValidator'
+
+export {EnumJSONSchema, JSONSchema, NamedEnumJSONSchema, CustomTypeJSONSchema} from './types/JSONSchema'
+
+export interface Options {
+  /**
+   * [$RefParser](https://github.com/BigstickCarpet/json-schema-ref-parser) Options, used when resolving `$ref`s
+   */
+  $refOptions: $RefOptions
+  /**
+   * Default value for additionalProperties, when it is not explicitly set.
+   */
+  additionalProperties: boolean
+  /**
+   * Disclaimer comment prepended to the top of each generated file.
+   */
+  bannerComment: string
+  /**
+   * Root directory for resolving [`$ref`](https://tools.ietf.org/id/draft-pbryan-zyp-json-ref-03.html)s.
+   */
+  cwd: string
+  /**
+   * Declare external schemas referenced via `$ref`?
+   */
+  declareExternallyReferenced: boolean
+  /**
+   * Prepend enums with [`const`](https://www.typescriptlang.org/docs/handbook/enums.html#computed-and-constant-members)?
+   */
+  enableConstEnums: boolean
+  /**
+   * Format code? Set this to `false` to improve performance.
+   */
+  format: boolean
+  /**
+   * Ignore maxItems and minItems for `array` types, preventing tuples being generated.
+   */
+  ignoreMinAndMaxItems: boolean
+  /**
+   * Maximum number of unioned tuples to emit when representing bounded-size array types,
+   * before falling back to emitting unbounded arrays. Increase this to improve precision
+   * of emitted types, decrease it to improve performance, or set it to `-1` to ignore
+   * `minItems` and `maxItems`.
+   */
+  maxItems: number
+  /**
+   * Use `prefixItems` and `items` instead of `items` and `additionalItems` for tuple validation. This change was introduced in the 2020-12 Release Notes of the
+   * JSON Schema specification. [Read more about this](https://json-schema.org/draft/2020-12/release-notes#2020-12-release-notes)
+   */
+  usePrefixItems: boolean
+  /**
+   * Append all index signatures with `| undefined` so that they are strictly typed.
+   *
+   * This is required to be compatible with `strictNullChecks`.
+   */
+  strictIndexSignatures: boolean
+  /**
+   * A [Prettier](https://prettier.io/docs/en/options.html) configuration.
+   */
+  style: PrettierOptions
+  /**
+   * Generate code for `definitions` that aren't referenced by the schema?
+   */
+  unreachableDefinitions: boolean
+  /**
+   * Generate unknown type instead of any
+   */
+  unknownAny: boolean
+}
+
+export const DEFAULT_OPTIONS: Options = {
+  $refOptions: {},
+  additionalProperties: true, // TODO: default to empty schema (as per spec) instead
+  bannerComment: `/* eslint-disable */
+/**
+* This file was automatically generated by json-schema-to-typescript.
+* DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,
+* and run json-schema-to-typescript to regenerate this file.
+*/`,
+  cwd: process.cwd(),
+  declareExternallyReferenced: true,
+  enableConstEnums: true,
+  format: true,
+  ignoreMinAndMaxItems: false,
+  maxItems: 20,
+  usePrefixItems: false,
+  strictIndexSignatures: false,
+  style: {
+    bracketSpacing: false,
+    printWidth: 120,
+    semi: true,
+    singleQuote: false,
+    tabWidth: 2,
+    trailingComma: 'none',
+    useTabs: false,
+  },
+  unreachableDefinitions: false,
+  unknownAny: true,
+}
+
+export function compileFromFile(filename: string, options: Partial<Options> = DEFAULT_OPTIONS): Promise<string> {
+  const contents = Try(
+    () => readFileSync(filename),
+    () => {
+      throw new ReferenceError(`Unable to read file "${filename}"`)
+    },
+  )
+  const schema = Try<JSONSchema4>(
+    () => JSON.parse(contents.toString()),
+    () => {
+      throw new TypeError(`Error parsing JSON in file "${filename}"`)
+    },
+  )
+  return compile(schema, stripExtension(filename), {cwd: dirname(filename), ...options})
+}
+
+export async function compile(schema: JSONSchema4, name: string, options: Partial<Options> = {}): Promise<string> {
+  validateOptions(options)
+
+  const _options = merge({}, DEFAULT_OPTIONS, options)
+
+  const start = Date.now()
+  function time() {
+    return `(${Date.now() - start}ms)`
+  }
+
+  // normalize options
+  if (!endsWith(_options.cwd, '/')) {
+    _options.cwd += '/'
+  }
+
+  // Initial clone to avoid mutating the input
+  const _schema = cloneDeep(schema)
+
+  const {dereferencedPaths, dereferencedSchema} = await dereference(_schema, _options)
+  if (process.env.VERBOSE) {
+    if (isDeepStrictEqual(_schema, dereferencedSchema)) {
+      log('green', 'dereferencer', time(), '✅ No change')
+    } else {
+      log('green', 'dereferencer', time(), '✅ Result:', dereferencedSchema)
+    }
+  }
+
+  const linked = link(dereferencedSchema)
+  if (process.env.VERBOSE) {
+    log('green', 'linker', time(), '✅ No change')
+  }
+
+  const errors = validate(linked, name)
+  if (errors.length) {
+    errors.forEach(_ => error(_))
+    throw new ValidationError()
+  }
+  if (process.env.VERBOSE) {
+    log('green', 'validator', time(), '✅ No change')
+  }
+
+  const normalized = normalize(linked, dereferencedPaths, name, _options)
+  log('yellow', 'normalizer', time(), '✅ Result:', normalized)
+
+  const parsed = parse(normalized, _options)
+  log('blue', 'parser', time(), '✅ Result:', parsed)
+
+  const optimized = optimize(parsed, _options)
+  log('cyan', 'optimizer', time(), '✅ Result:', optimized)
+
+  const generated = generate(optimized, _options)
+  log('magenta', 'generator', time(), '✅ Result:', generated)
+
+  const formatted = format(generated, _options)
+  log('white', 'formatter', time(), '✅ Result:', formatted)
+
+  return formatted
+}
+
+export class ValidationError extends Error {}