diff --git a/src/index.ts b/src/index.ts
index 13386df..f21e004 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,7 +5,7 @@ import * as path from 'path'
  * Json loader support for *.json files.
  * See: https://github.com/webpack/json-loader
  */
-export = function json(exclude: Array<string> = null) {
+export = function json({exclude = null}) {
   return function json(this: WebpackConfig): WebpackConfig {
     return {
       module: {