diff --git a/src/general.ts b/src/general.ts
index 7790394..ea4035b 100644
--- a/src/general.ts
+++ b/src/general.ts
@@ -12,9 +12,9 @@ import * as client from 'cheerio-httpcli';
 client.set('referer', false);
 client.set('timeout', 10000);
 
-import ISummary from './isummary';
+import Summary from './summary';
 
-export default async (url: URL.Url): Promise<ISummary> => {
+export default async (url: URL.Url): Promise<Summary> => {
 	const res = await client.fetch(url.href);
 
 	if (res.error) {
diff --git a/src/index.ts b/src/index.ts
index 61ab494..a56053c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,16 +6,19 @@
 import * as URL from 'url';
 import requireAll = require('require-all');
 import tracer from 'trace-redirect';
-import ISummary from './isummary';
+import Summary from './summary';
 import IPlugin from './iplugin';
 import general from './general';
 
 // Load builtin plugins
-const builtinPlugins = requireAll({
+const _builtinPlugins = requireAll({
 	dirname: __dirname + '/plugins'
 }) as { [key: string]: IPlugin };
 
-export interface IOptions {
+const builtinPlugins = Object.keys(_builtinPlugins)
+	.map(key => _builtinPlugins[key]);
+
+type Options = {
 	/**
 	 * リダイレクトを追跡するか否か
 	 */
@@ -25,27 +28,25 @@ export interface IOptions {
 	 * Custom Plugins
 	 */
 	plugins?: IPlugin[];
-}
+};
 
-type Result = ISummary & {
+type Result = Summary & {
 	url: string;
 };
 
 /**
  * Summary an web page
  * @param  {string}          url     URL of web page you want to summary
- * @param  {IOptions}        options The options
+ * @param  {Options}         options The options
  * @return {Promise<Result>} Promised summary
  */
-export default async (url: string, options: IOptions): Promise<Result> => {
+export default async (url: string, options: Options): Promise<Result> => {
 	const opts = Object.assign({
 		followRedirects: true,
 		plugins: null
-	}, options) as IOptions;
+	}, options) as Options;
 
-	const plugins = Object.keys(builtinPlugins)
-		.map(key => builtinPlugins[key])
-		.concat(opts.plugins || []);
+	const plugins = builtinPlugins.concat(opts.plugins || []);
 
 	// Follow redirects
 	const actualUrl = opts.followRedirects ? await tracer(url) : url;
diff --git a/src/plugins/amazon.ts b/src/plugins/amazon.ts
index 7007c8f..2684c71 100644
--- a/src/plugins/amazon.ts
+++ b/src/plugins/amazon.ts
@@ -4,7 +4,7 @@ import * as client from 'cheerio-httpcli';
 client.set('referer', false);
 client.set('timeout', 10000);
 
-export function test (url: URL.Url) {
+export function test(url: URL.Url) {
 	return url.hostname === 'www.amazon.com' ||
 	url.hostname === 'www.amazon.co.jp' ||
 	url.hostname === 'www.amazon.ca' ||
@@ -21,7 +21,7 @@ export function test (url: URL.Url) {
 	url.hostname === 'www.amazon.au'
 };
 
-export async function summary (url: URL.Url) {
+export async function summary(url: URL.Url) {
 	const res = await client.fetch(url.href);
 	const $: client.CheerioStaticEx = res.$;
 
diff --git a/src/plugins/wikipedia.ts b/src/plugins/wikipedia.ts
index efea9b8..0dd42d6 100644
--- a/src/plugins/wikipedia.ts
+++ b/src/plugins/wikipedia.ts
@@ -5,11 +5,11 @@ import clip from './../utils/clip';
 
 const log = debug('summaly:plugins:wikipedia');
 
-export function test (url: URL.Url) {
+export function test(url: URL.Url) {
 	return /\.wikipedia\.org$/.test(url.hostname);
 };
 
-export function summary (url: URL.Url) {
+export function summary(url: URL.Url) {
 	return new Promise((res, rej) => {
 		const lang = url.host.split('.')[0];
 		const title = url.pathname.split('/')[2];
diff --git a/src/isummary.ts b/src/summary.ts
similarity index 67%
rename from src/isummary.ts
rename to src/summary.ts
index c6567b4..e5921fd 100644
--- a/src/isummary.ts
+++ b/src/summary.ts
@@ -1,4 +1,4 @@
-interface ISummary {
+type Summary = {
 	description: string;
 	icon: string;
 	sitename: string;
@@ -6,4 +6,4 @@ interface ISummary {
 	title: string;
 }
 
-export default ISummary;
+export default Summary;