diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..3e1529c
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,39 @@
+/// <reference types="node"/>
+import * as fs from 'fs';
+
+export interface Options {
+	/**
+	 * Directory [permissions](https://x-team.com/blog/file-system-permissions-umask-node-js/).
+	 *
+	 * @default 0o777 & (~process.umask())
+	 */
+	readonly mode?: number;
+
+	/**
+	 * Use a custom `fs` implementation. For example [`graceful-fs`](https://github.com/isaacs/node-graceful-fs).
+	 *
+	 * Using a custom `fs` implementation will block the use of the native `recursive` option if `fs.mkdir` or `fs.mkdirSync` is not the native function.
+	 *
+	 * @default require('fs')
+	 */
+	readonly fs?: typeof fs;
+}
+
+/**
+ * Make a directory and its parents if needed - Think `mkdir -p`.
+ *
+ * @param path - Directory to create.
+ * @returns A `Promise` for the path to the created directory.
+ */
+export default function makeDir(
+	path: string,
+	options?: Options
+): Promise<string>;
+
+/**
+ * Synchronously make a directory and its parents if needed - Think `mkdir -p`.
+ *
+ * @param path - Directory to create.
+ * @returns The path to the created directory.
+ */
+export function sync(path: string, options?: Options): string;
diff --git a/index.js b/index.js
index 7f2e0cf..4d95c91 100644
--- a/index.js
+++ b/index.js
@@ -36,7 +36,7 @@ const permissionError = pth => {
 	return error;
 };
 
-module.exports = (input, options) => Promise.resolve().then(() => {
+const makeDir = (input, options) => Promise.resolve().then(() => {
 	checkPath(input);
 	options = Object.assign({}, defaults, options);
 
@@ -84,6 +84,9 @@ module.exports = (input, options) => Promise.resolve().then(() => {
 	return make(path.resolve(input));
 });
 
+module.exports = makeDir;
+module.exports.default = makeDir;
+
 module.exports.sync = (input, options) => {
 	checkPath(input);
 	options = Object.assign({}, defaults, options);
diff --git a/index.test-d.ts b/index.test-d.ts
new file mode 100644
index 0000000..9555f6d
--- /dev/null
+++ b/index.test-d.ts
@@ -0,0 +1,22 @@
+import {expectType} from 'tsd-check';
+import makeDir, {sync as makeDirSync} from '.';
+import * as fs from 'fs';
+import * as gfs from 'graceful-fs';
+
+// MakeDir
+expectType<Promise<string>>(makeDir('path/to/somewhere'));
+
+expectType<Promise<string>>(
+	makeDir('path/to/somewhere', {mode: parseInt('777', 8)})
+);
+expectType<Promise<string>>(makeDir('path/to/somewhere', {fs}));
+expectType<Promise<string>>(makeDir('path/to/somewhere', {fs: gfs}));
+
+// MakeDir (sync)
+expectType<string>(makeDirSync('path/to/somewhere'));
+
+expectType<string>(
+	makeDirSync('path/to/somewhere', {mode: parseInt('777', 8)})
+);
+expectType<string>(makeDirSync('path/to/somewhere', {fs}));
+expectType<string>(makeDirSync('path/to/somewhere', {fs: gfs}));
diff --git a/package.json b/package.json
index e799421..71f735c 100644
--- a/package.json
+++ b/package.json
@@ -13,10 +13,11 @@
 		"node": ">=6"
 	},
 	"scripts": {
-		"test": "xo && nyc ava"
+		"test": "xo && nyc ava && tsd-check"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"mkdir",
@@ -44,12 +45,15 @@
 		"semver": "^5.6.0"
 	},
 	"devDependencies": {
+		"@types/graceful-fs": "^4.1.3",
+		"@types/node": "^11.10.4",
 		"ava": "^1.2.0",
 		"codecov": "^3.0.0",
 		"graceful-fs": "^4.1.11",
 		"nyc": "^13.1.0",
 		"path-type": "^3.0.0",
 		"tempy": "^0.2.1",
+		"tsd-check": "^0.3.0",
 		"xo": "^0.24.0"
 	}
 }