diff --git a/index.js b/index.js
index e2369b5..8e79b94 100644
--- a/index.js
+++ b/index.js
@@ -48,7 +48,7 @@ module.exports.Route = Route
 /**
  * Initialize a new `Router` with the given `options`.
  *
- * @param {object} options
+ * @param {object} [options]
  * @return {Router} which is a callable function
  * @public
  */