diff --git a/README.md b/README.md
index ba25348..920192a 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,8 @@ A `Promise.try` shim for ES6 Promises.
 
 The goal of this module is to be *functionally equivalent* to Bluebird's `Promise.try` implementation. If you find that it behaves differently in some way, please file a bug.
 
+__This module requires ES6 Promises to be available in your environment.__ If you are targeting a platform that doesn't (always) provide ES6 Promises natively, you will need to use a polyfill like [`es6-promise`](https://www.npmjs.com/package/es6-promise).
+
 ## License
 
 [WTFPL](http://www.wtfpl.net/txt/copying/) or [CC0](https://creativecommons.org/publicdomain/zero/1.0/), whichever you prefer. A donation and/or attribution are appreciated, but not required.