diff --git a/README.md b/README.md
index 244562b9..a9bbe911 100644
--- a/README.md
+++ b/README.md
@@ -95,7 +95,7 @@ TODO:
 * Requires `IntersectionObserver` to be supported (see [CanIUse](https://caniuse.com/#feat=intersectionobserver)). We recommend conditionally polyfilling this feature with a service like Polyfill.io:
 
 ```html
-<script src="https://polyfill.io/v2/polyfill.min.js?features=IntersectionObserver"></script>
+<script src="https://polyfill.io/v3/polyfill.min.js?features=IntersectionObserver"></script>
 ```
 
 Alternatively, see the [Intersection Observer polyfill](https://github.com/w3c/IntersectionObserver/tree/master/polyfill).