diff --git a/index.d.ts b/index.d.ts
index b7fae88..29c14ec 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -2,5 +2,6 @@
  * Delegates event to a selector.
  */
 declare type CombinedElements = EventTarget | EventTarget[] | NodeListOf<Element> | String;
-declare const _default: (elements: CombinedElements, selector: string, type: string, callback: () => any, useCapture: boolean | AddEventListenerOptions) => any;
-export = _default;
+declare function delegate(selector: string, type: string, callback?: Function, useCapture?: boolean | AddEventListenerOptions): object;
+declare function delegate(elements: CombinedElements, selector: string, type: string, callback?: Function, useCapture?: boolean | AddEventListenerOptions): object;
+export = delegate;
diff --git a/index.ts b/index.ts
index 06e6dfa..bd9e92f 100644
--- a/index.ts
+++ b/index.ts
@@ -4,8 +4,8 @@ function _delegate(
 	element: EventTarget,
 	selector: string,
 	type: string,
-	callback: () => any,
-	useCapture: boolean | AddEventListenerOptions
+	callback?: Function,
+	useCapture?: boolean | AddEventListenerOptions
 ) {
 	const listenerFn = event => {
 		event.delegateTarget = event.target.closest(selector);
@@ -64,12 +64,25 @@ function _delegate(
  * Delegates event to a selector.
  */
 type CombinedElements = EventTarget | EventTarget[] | NodeListOf<Element> | String;
-export = function delegate(
+function delegate(
+	selector: string,
+	type: string,
+	callback?: Function,
+	useCapture?: boolean | AddEventListenerOptions
+): object;
+function delegate(
 	elements: CombinedElements,
 	selector: string,
 	type: string,
-	callback: () => any,
-	useCapture: boolean | AddEventListenerOptions
+	callback?: Function,
+	useCapture?: boolean | AddEventListenerOptions
+	): object;
+function delegate(
+	elements,
+	selector,
+	type,
+	callback?,
+	useCapture?
 ) {
 	// Handle the regular Element usage
 	if (typeof (elements as EventTarget).addEventListener === 'function') {
@@ -78,7 +91,7 @@ export = function delegate(
 
 	// Handle Element-less usage, it defaults to global delegation
 	if (typeof type === 'function') {
-		return _delegate(document, elements as string, selector as string, type as () => any, callback as boolean | AddEventListenerOptions);
+		return _delegate(document, elements as string, selector as string, type as Function, callback as boolean | AddEventListenerOptions);
 	}
 
 	// Handle Selector-based usage
@@ -91,3 +104,5 @@ export = function delegate(
 		return _delegate(element, selector, type, callback, useCapture);
 	});
 }
+
+export = delegate;
diff --git a/package.json b/package.json
index e1970f7..f089500 100644
--- a/package.json
+++ b/package.json
@@ -23,7 +23,7 @@
 	"scripts": {
 		"test": "xo !index.js && ava && tsc",
 		"prepublish": "tsc",
-		"preversion": "tsc"
+		"build": "tsc"
 	},
 	"xo": {
 		"envs": [