diff --git a/.npmignore b/.npmignore
deleted file mode 100644
index 158f8f1..0000000
--- a/.npmignore
+++ /dev/null
@@ -1,9 +0,0 @@
-node_modules
-coverage
-test
-example
-.eslintrc.yaml
-package-lock.json
-yarn.lock
-coverage
-.nyc_output
\ No newline at end of file
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..664fb1f
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,15 @@
+type LimiterCallback = () => void;
+type AsyncJobCallback = (cb: LimiterCallback) => void | any;
+type OnDoneCallback = (...args: any) => any;
+
+declare class Queue {
+    constructor(options?: {concurrency?: number});
+    readonly length: number;
+    push(...items: AsyncJobCallback[]): number;
+    splice(start: number, deleteCount?: number): AsyncJobCallback[];
+    splice(start: number, deleteCount: number, ...items: AsyncJobCallback[]): AsyncJobCallback[];
+    unshift(...items: AsyncJobCallback[]): number;
+    onDone(cb: OnDoneCallback): void;
+}
+
+export default Queue;
diff --git a/index.js b/index.js
index d5c8a38..55065e0 100644
--- a/index.js
+++ b/index.js
@@ -1,64 +1,96 @@
 'use strict';
 
-function Queue(options) {
-  if (!(this instanceof Queue)) {
-    return new Queue(options);
-  }
+/**
+ * @typedef {() => void} LimiterCallback
+ * @typedef {(cb: LimiterCallback) => void | any} AsyncJobCallback
+ * @typedef {(...args: any) => any} OnDoneCallback
+ *
+ * @extends Array<AsyncJobCallback>
+ */
+class Queue {
+  /**
+   * @param {{ concurrency: number; }} [options={ concurrency: Infinity }]
+   */
+  constructor(options) {
+    /** @readonly @type {number} */
+    this.concurrency = (options || {}).concurrency || Infinity;
 
-  options = options || {};
-  this.concurrency = options.concurrency || Infinity;
-  this.pending = 0;
-  this.jobs = [];
-  this.onDoneCbs = [];
-  this._done = done.bind(this);
-  this._run = run.bind(this);
-}
+    /** @private @type {number} */
+    this.pending = 0;
 
-// Called upon completion of a job. Calls run() again
-// to pluck the next job off the queue, if it exists.
-function done() {
-  this.pending--;
-  this._run();
-}
+    /** @private @type {AsyncJobCallback[]} */
+    this.jobs = [];
+
+    /** @private @type {OnDoneCallback[]} */
+    this.onDoneCbs = [];
 
-function run() {
-  // Do we have capacity for jobs?
-  // If so, start them, uip to the concurrency limit
-  while (this.pending < this.concurrency && this.jobs.length) {
-    this.pending++;
-    var job = this.jobs.shift();
-    job(this._done);
+    this.push = this._extendFromArray('push');
+    this.splice = this._extendFromArray('splice');
+    this.unshift = this._extendFromArray('unshift');
+
+    this._run = this._run.bind(this);
+    this._done = this._done.bind(this);
   }
 
-  // Are we done processing all jobs? If so, call onDone callbacks
-  while (this.length === 0 && this.onDoneCbs.length) {
-    var cb = this.onDoneCbs.pop();
-    cb();
+  get length() {
+    return this.pending + this.jobs.length;
   }
-}
 
-// Replicate popular array methods to queue up jobs.
-['push', 'splice', 'unshift'].forEach(function(method) {
-  Queue.prototype[method] = function() {
-    var methodResult = Array.prototype[method].apply(this.jobs, arguments);
-    process.nextTick(this._run);
-    return methodResult;
-  };
-});
+  /**
+   * Called upon completion of a job. Calls _run() again
+   * to pluck the next job off the queue, if it exists.
+   * @private
+   */
+  _done() {
+    this.pending--;
+    this._run();
+  }
 
-Object.defineProperty(Queue.prototype, 'length', {
-  get: function() {
-    return this.pending + this.jobs.length;
+  /** @private */
+  _run() {
+    // Do we have capacity for jobs?
+    // If so, start them, uip to the concurrency limit
+    while (this.pending < this.concurrency && this.jobs.length) {
+      this.pending++;
+      const job = this.jobs.shift();
+      job && job(this._done);
+    }
+
+    // Are we done processing all jobs? If so, call onDone callbacks
+    while (this.length === 0 && this.onDoneCbs.length) {
+      var cb = this.onDoneCbs.pop();
+      cb && cb();
+    }
+  }
+
+  /**
+   * Replicate popular array methods to queue up jobs.
+   * @private
+   * @param {string} method
+   */
+  _extendFromArray(method) {
+    return function() {
+      // @ts-ignore
+      const methodResult = Array.prototype[method].apply(this.jobs, arguments);
+      // @ts-ignore
+      process.nextTick(this._run);
+      return methodResult;
+    };
   }
-});
 
-// Simply adds a callback to the end of the job list
-Queue.prototype.onDone = function(cb) {
-  if (typeof cb === 'function') this.onDoneCbs.push(cb);
-  // If there are no jobs in the queue, this will call `cb()` in the next tick.
-  // This is intended for that there is predictable behavior even when running a
-  // job list of length 0.
-  process.nextTick(this._run);
-};
+  /**
+   * Simply adds a callback to the end of the job list
+   * @param {any} cb
+   */
+  onDone(cb) {
+    if (typeof cb === 'function') this.onDoneCbs.push(cb);
+    // If there are no jobs in the queue,
+    // this will call `cb()` in the next tick.
+    // This is intended for that there is predictable
+    // behavior even when running a job list of length 0.
+    // @ts-ignore
+    process.nextTick(this._run);
+  }
+}
 
 module.exports = Queue;
diff --git a/package.json b/package.json
index 37033dc..be5e471 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,12 @@
     "example": "node example",
     "lint": "eslint ."
   },
+  "files": [
+    "index.js",
+    "index.d.ts"
+  ],
+  "main": "index.js",
+  "types": "index.d.ts",
   "repository": "https://github.com/strml/async-limiter.git",
   "author": "Samuel Reed <samuel.trace.reed@gmail.com",
   "license": "MIT"
diff --git a/test/throttleSpec.js b/test/throttleSpec.js
index a74657d..dcd2a61 100644
--- a/test/throttleSpec.js
+++ b/test/throttleSpec.js
@@ -153,7 +153,7 @@ describe('Async-Limiter', function(endTest) {
   });
 
   it('has a length property that follows concurrency', function(endTest) {
-    var t = Limiter({ concurrency: 1 });
+    var t = new Limiter({ concurrency: 1 });
 
     t.push(function(cb) {
       setTimeout(function() {