diff --git a/package.json b/package.json
index 9acba87..36e7b52 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
     "url": "https://github.com/streamich/fs-monkey.git"
   },
   "scripts": {
-    "build": "babel src --out-dir lib",
+    "build": "babel src --out-dir lib --copy-files",
     "test": "jest"
   },
   "dependencies": {},
diff --git a/src/index.d.ts b/src/index.d.ts
new file mode 100644
index 0000000..2699484
--- /dev/null
+++ b/src/index.d.ts
@@ -0,0 +1,113 @@
+import Module from "module"
+
+declare module "fs-monkey" {
+	/**
+	 * fs-like object
+	 *
+	 * @export
+	 * @interface Volume
+	 */
+	export interface Volume {
+		// Recongized sync methods
+		renameSync?: Function
+		ftruncateSync?: Function
+		truncateSync?: Function
+		chownSync?: Function
+		fchownSync?: Function
+		lchownSync?: Function
+		chmodSync?: Function
+		fchmodSync?: Function
+		lchmodSync?: Function
+		statSync?: Function
+		lstatSync?: Function
+		fstatSync?: Function
+		linkSync?: Function
+		symlinkSync?: Function
+		readlinkSync?: Function
+		realpathSync?: Function
+		unlinkSync?: Function
+		rmdirSync?: Function
+		mkdirSync?: Function
+		mkdirpSync?: Function
+		readdirSync?: Function
+		closeSync?: Function
+		openSync?: Function
+		utimesSync?: Function
+		futimesSync?: Function
+		fsyncSync?: Function
+		writeSync?: Function
+		readSync?: Function
+		readFileSync?: Function
+		writeFileSync?: Function
+		appendFileSync?: Function
+		existsSync?: Function
+		accessSync?: Function
+		fdatasyncSync?: Function
+		mkdtempSync?: Function
+		copyFileSync?: Function
+		rmSync?: Function
+		createReadStream?: Function
+		createWriteStream?: Function
+		// Recongized async methods
+		rename?: Function
+		ftruncate?: Function
+		truncate?: Function
+		chown?: Function
+		fchown?: Function
+		lchown?: Function
+		chmod?: Function
+		fchmod?: Function
+		lchmod?: Function
+		stat?: Function
+		lstat?: Function
+		fstat?: Function
+		link?: Function
+		symlink?: Function
+		readlink?: Function
+		realpath?: Function
+		unlink?: Function
+		rmdir?: Function
+		mkdir?: Function
+		mkdirp?: Function
+		readdir?: Function
+		close?: Function
+		open?: Function
+		utimes?: Function
+		futimes?: Function
+		fsync?: Function
+		write?: Function
+		read?: Function
+		readFile?: Function
+		writeFile?: Function
+		appendFile?: Function
+		exists?: Function
+		access?: Function
+		fdatasync?: Function
+		mkdtemp?: Function
+		copyFile?: Function
+		rm?: Function
+		watchFile?: Function
+		unwatchFile?: Function
+		watch?: Function
+	}
+
+	/**
+	 * Rewrites Node's filesystem module `fs` with fs-like object.
+	 *
+	 * @export
+	 * @param {Volume} vol fs-like object
+	 * @param {*} [fs] a filesystem to patch, defaults to `require('fs')`
+	 * @return {*}  {() => void} function to reset fs state
+	 */
+	export function patchFs(vol: Volume, fs?: Module): () => void
+
+	/**
+	 * Patches Node's `module` module to use a given fs-like object `vol` for module loading.
+	 *
+	 * @export
+	 * @param {Volume} vol fs-like object
+	 * @param {boolean} [unixifyPaths] whether to convert Windows paths to unix style paths, defaults to `false`
+	 * @param {Module} [module] a module to patch, defaults to `require('module')`
+	 */
+	export function patchRequire(vol: Volume, unixifyPaths?: boolean, module?: Module): void
+}