diff --git a/README.md b/README.md
index 2f0dd74..2c1ea68 100644
--- a/README.md
+++ b/README.md
@@ -119,6 +119,22 @@ handleResponse('some', 'args') // TypeError: Callback is required
 
 Note the __vargs.strict__ call.
 
+With ES6 default parameters:
+vargs-callback uses Function.length to find the correct position for the callback. The length parameter only includes parameters before the first one with a default value so you will need to set the length parameter for functions with default arguments for vargs-callback to work.
+
+```js
+var vargs = require('vargs-callback')
+
+function openTheDoor(door, options = {speed: 1} , callback) {
+    // actual function code using parameters
+    // options will be {speed: 1} if only door and callback given
+    if (door.isOpen) return
+    // ...
+}
+
+Object.defineProperty(openTheDoor, 'length', { value: 3 })
+openTheDoor = vargs(openTheDoor) // Decorate global function
+```
 
 ## The Rules