diff --git a/index.d.ts b/index.d.ts
index 2a50665..463fb40 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,183 +1,216 @@
-export interface Options {
-	/**
-	 * @default 'http:'
-	 */
-	readonly defaultProtocol?: string;
+declare namespace normalizeUrl {
+	interface Options {
+		/**
+		@default 'http:'
+		*/
+		readonly defaultProtocol?: string;
 
-	/**
-	 * Prepends `defaultProtocol` to the URL if it's protocol-relative.
-	 *
-	 * @default true
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('//sindresorhus.com:80/');
-	 * //=> 'http://sindresorhus.com'
-	 *
-	 * normalizeUrl('//sindresorhus.com:80/', {normalizeProtocol: false});
-	 * //=> '//sindresorhus.com'
-	 */
-	readonly normalizeProtocol?: boolean;
+		/**
+		Prepends `defaultProtocol` to the URL if it's protocol-relative.
 
-	/**
-	 * Normalizes `https:` URLs to `http:`.
-	 *
-	 * @default false
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('https://sindresorhus.com:80/');
-	 * //=> 'https://sindresorhus.com'
-	 *
-	 * normalizeUrl('https://sindresorhus.com:80/', {forceHttp: true});
-	 * //=> 'http://sindresorhus.com'
-	 */
-	readonly forceHttp?: boolean;
+		@default true
 
-	/**
-	 * Normalizes `http:` URLs to `https:`.
-	 *
-	 * This option can't be used with the `forceHttp` option at the same time.
-	 *
-	 * @default false
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('https://sindresorhus.com:80/');
-	 * //=> 'https://sindresorhus.com'
-	 *
-	 * normalizeUrl('http://sindresorhus.com:80/', {forceHttps: true});
-	 * //=> 'https://sindresorhus.com'
-	 */
-	readonly forceHttps?: boolean;
+		@example
+		```
+		normalizeUrl('//sindresorhus.com:80/');
+		//=> 'http://sindresorhus.com'
 
-	/**
-	 * Strip the [authentication](https://en.wikipedia.org/wiki/Basic_access_authentication) part of a URL.
-	 *
-	 * @default true
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('user:password@sindresorhus.com');
-	 * //=> 'https://sindresorhus.com'
-	 *
-	 * normalizeUrl('user:password@sindresorhus.com', {stripAuthentication: false});
-	 * //=> 'https://user:password@sindresorhus.com'
-	 */
-	readonly stripAuthentication?: boolean;
+		normalizeUrl('//sindresorhus.com:80/', {normalizeProtocol: false});
+		//=> '//sindresorhus.com'
+		```
+		*/
+		readonly normalizeProtocol?: boolean;
 
-	/**
-	 * Removes hash from the URL.
-	 *
-	 * @default false
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('sindresorhus.com/about.html#contact');
-	 * //=> 'http://sindresorhus.com/about.html#contact'
-	 *
-	 * normalizeUrl('sindresorhus.com/about.html#contact', {stripHash: true});
-	 * //=> 'http://sindresorhus.com/about.html'
-	 */
-	readonly stripHash?: boolean;
+		/**
+		Normalizes `https:` URLs to `http:`.
 
-	/**
-	 * Removes HTTP(S) protocol from an URL `http://sindresorhus.com` → `sindresorhus.com`.
-	 *
-	 * @default false
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('https://sindresorhus.com');
-	 * //=> 'https://sindresorhus.com'
-	 *
-	 * normalizeUrl('sindresorhus.com', {stripProtocol: true});
-	 * //=> 'sindresorhus.com'
-	 */
-	readonly stripProtocol?: boolean;
+		@default false
 
-	/**
-	 * Removes `www.` from the URL.
-	 *
-	 * @default true
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('http://www.sindresorhus.com');
-	 * //=> 'http://sindresorhus.com'
-	 *
-	 * normalizeUrl('http://www.sindresorhus.com', {stripWWW: false});
-	 * //=> 'http://www.sindresorhus.com'
-	 */
-	readonly stripWWW?: boolean;
+		@example
+		```
+		normalizeUrl('https://sindresorhus.com:80/');
+		//=> 'https://sindresorhus.com'
 
-	/**
-	 * Removes query parameters that matches any of the provided strings or regexes.
-	 *
-	 * @default [/^utm_\w+/i]
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('www.sindresorhus.com?foo=bar&ref=test_ref', {
-	 * 	removeQueryParameters: ['ref']
-	 * });
-	 * //=> 'http://sindresorhus.com/?foo=bar'
-	 */
-	readonly removeQueryParameters?: (RegExp | string)[];
+		normalizeUrl('https://sindresorhus.com:80/', {forceHttp: true});
+		//=> 'http://sindresorhus.com'
+		```
+		*/
+		readonly forceHttp?: boolean;
 
-	/**
-	 * Removes trailing slash.
-	 *
-	 * **Note**: Trailing slash is always removed if the URL doesn't have a pathname.
-	 *
-	 * @default true
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('http://sindresorhus.com/redirect/');
-	 * //=> 'http://sindresorhus.com/redirect'
-	 *
-	 * normalizeUrl('http://sindresorhus.com/redirect/', {removeTrailingSlash: false});
-	 * //=> 'http://sindresorhus.com/redirect/'
-	 *
-	 * normalizeUrl('http://sindresorhus.com/', {removeTrailingSlash: false});
-	 * //=> 'http://sindresorhus.com'
-	 */
-	readonly removeTrailingSlash?: boolean;
+		/**
+		Normalizes `http:` URLs to `https:`.
 
-	/**
-	 * Removes the default directory index file from path that matches any of the provided strings or regexes.
-	 * When `true`, the regex `/^index\.[a-z]+$/` is used.
-	 *
-	 * @default false
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('www.sindresorhus.com/foo/default.php', {
-	 * 	removeDirectoryIndex: [/^default\.[a-z]+$/]
-	 * });
-	 * //=> 'http://sindresorhus.com/foo'
-	 */
-	readonly removeDirectoryIndex?: (RegExp | string)[];
+		This option can't be used with the `forceHttp` option at the same time.
 
-	/**
-	 * Sorts the query parameters alphabetically by key.
-	 *
-	 * @default true
-	 *
-	 * @example
-	 *
-	 * normalizeUrl('www.sindresorhus.com?b=two&a=one&c=three', {
-	 * 	sortQueryParameters: false
-	 * });
-	 * //=> 'http://sindresorhus.com/?b=two&a=one&c=three'
-	 */
-	readonly sortQueryParameters?: boolean;
+		@default false
+
+		@example
+		```
+		normalizeUrl('https://sindresorhus.com:80/');
+		//=> 'https://sindresorhus.com'
+
+		normalizeUrl('http://sindresorhus.com:80/', {forceHttps: true});
+		//=> 'https://sindresorhus.com'
+		```
+		*/
+		readonly forceHttps?: boolean;
+
+		/**
+		Strip the [authentication](https://en.wikipedia.org/wiki/Basic_access_authentication) part of a URL.
+
+		@default true
+
+		@example
+		```
+		normalizeUrl('user:password@sindresorhus.com');
+		//=> 'https://sindresorhus.com'
+
+		normalizeUrl('user:password@sindresorhus.com', {stripAuthentication: false});
+		//=> 'https://user:password@sindresorhus.com'
+		```
+		*/
+		readonly stripAuthentication?: boolean;
+
+		/**
+		Removes hash from the URL.
+
+		@default false
+
+		@example
+		```
+		normalizeUrl('sindresorhus.com/about.html#contact');
+		//=> 'http://sindresorhus.com/about.html#contact'
+
+		normalizeUrl('sindresorhus.com/about.html#contact', {stripHash: true});
+		//=> 'http://sindresorhus.com/about.html'
+		```
+		*/
+		readonly stripHash?: boolean;
+
+		/**
+		Removes HTTP(S) protocol from an URL `http://sindresorhus.com` → `sindresorhus.com`.
+
+		@default false
+
+		@example
+		```
+		normalizeUrl('https://sindresorhus.com');
+		//=> 'https://sindresorhus.com'
+
+		normalizeUrl('sindresorhus.com', {stripProtocol: true});
+		//=> 'sindresorhus.com'
+		```
+		*/
+		readonly stripProtocol?: boolean;
+
+		/**
+		Removes `www.` from the URL.
+
+		@default true
+
+		@example
+		```
+		normalizeUrl('http://www.sindresorhus.com');
+		//=> 'http://sindresorhus.com'
+
+		normalizeUrl('http://www.sindresorhus.com', {stripWWW: false});
+		//=> 'http://www.sindresorhus.com'
+		```
+		*/
+		readonly stripWWW?: boolean;
+
+		/**
+		Removes query parameters that matches any of the provided strings or regexes.
+
+		@default [/^utm_\w+/i]
+
+		@example
+		```
+		normalizeUrl('www.sindresorhus.com?foo=bar&ref=test_ref', {
+			removeQueryParameters: ['ref']
+		});
+		//=> 'http://sindresorhus.com/?foo=bar'
+		```
+		*/
+		readonly removeQueryParameters?: (RegExp | string)[];
+
+		/**
+		Removes trailing slash.
+
+		__Note__: Trailing slash is always removed if the URL doesn't have a pathname.
+
+		@default true
+
+		@example
+		```
+		normalizeUrl('http://sindresorhus.com/redirect/');
+		//=> 'http://sindresorhus.com/redirect'
+
+		normalizeUrl('http://sindresorhus.com/redirect/', {removeTrailingSlash: false});
+		//=> 'http://sindresorhus.com/redirect/'
+
+		normalizeUrl('http://sindresorhus.com/', {removeTrailingSlash: false});
+		//=> 'http://sindresorhus.com'
+		```
+		*/
+		readonly removeTrailingSlash?: boolean;
+
+		/**
+		Removes the default directory index file from path that matches any of the provided strings or regexes.
+		When `true`, the regex `/^index\.[a-z]+$/` is used.
+
+		@default false
+
+		@example
+		```
+		normalizeUrl('www.sindresorhus.com/foo/default.php', {
+			removeDirectoryIndex: [/^default\.[a-z]+$/]
+		});
+		//=> 'http://sindresorhus.com/foo'
+		```
+		*/
+		readonly removeDirectoryIndex?: (RegExp | string)[];
+
+		/**
+		Sorts the query parameters alphabetically by key.
+
+		@default true
+
+		@example
+		```
+		normalizeUrl('www.sindresorhus.com?b=two&a=one&c=three', {
+			sortQueryParameters: false
+		});
+		//=> 'http://sindresorhus.com/?b=two&a=one&c=three'
+		```
+		*/
+		readonly sortQueryParameters?: boolean;
+	}
 }
 
-/**
- * [Normalize](https://en.wikipedia.org/wiki/URL_normalization) a URL.
- *
- * @param url - URL to normalize.
- */
-export default function normalizeUrl(url: string, options?: Options): string;
+declare const normalizeUrl: {
+	/**
+	[Normalize](https://en.wikipedia.org/wiki/URL_normalization) a URL.
+
+	@param url - URL to normalize.
+
+	@example
+	```
+	import normalizeUrl = require('normalize-url');
+
+	normalizeUrl('sindresorhus.com');
+	//=> 'http://sindresorhus.com'
+
+	normalizeUrl('HTTP://xn--xample-hva.com:80/?b=bar&a=foo');
+	//=> 'http://êxample.com/?a=foo&b=bar'
+	```
+	*/
+	(url: string, options?: normalizeUrl.Options): string;
+
+	// TODO: Remove this for the next major release, refactor the whole definition to:
+	// declare function normalizeUrl(url: string, options?: normalizeUrl.Options): string;
+	// export = normalizeUrl;
+	default: typeof normalizeUrl;
+};
+
+export = normalizeUrl;
diff --git a/index.js b/index.js
index d11ffb3..ac386a0 100644
--- a/index.js
+++ b/index.js
@@ -156,4 +156,5 @@ const normalizeUrl = (urlString, options) => {
 };
 
 module.exports = normalizeUrl;
+// TODO: Remove this for the next major release
 module.exports.default = normalizeUrl;
diff --git a/index.test-d.ts b/index.test-d.ts
index dad80be..104541f 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -1,5 +1,5 @@
-import {expectType} from 'tsd-check';
-import normalizeUrl from '.';
+import {expectType} from 'tsd';
+import normalizeUrl = require('.');
 
 expectType<string>(normalizeUrl('sindresorhus.com'));
 expectType<string>(normalizeUrl('HTTP://xn--xample-hva.com:80/?b=bar&a=foo'));
diff --git a/package.json b/package.json
index 4b968a3..f839057 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "normalize-url",
-	"version": "4.2.0",
+	"version": "4.3.0",
 	"description": "Normalize a URL",
 	"license": "MIT",
 	"repository": "sindresorhus/normalize-url",
@@ -13,7 +13,7 @@
 		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && nyc ava && tsd-check"
+		"test": "xo && nyc ava && tsd"
 	},
 	"files": [
 		"index.js",
@@ -35,10 +35,10 @@
 		"canonical"
 	],
 	"devDependencies": {
-		"ava": "^1.2.1",
-		"coveralls": "^3.0.0",
-		"nyc": "^13.1.0",
-		"tsd-check": "^0.3.0",
+		"ava": "^1.4.1",
+		"coveralls": "^3.0.3",
+		"nyc": "^13.3.0",
+		"tsd": "^0.7.2",
 		"xo": "^0.24.0"
 	}
 }