diff --git a/src/index.js b/src/index.js
index <HASH>..<HASH> 100644
--- a/src/index.js
+++ b/src/index.js
@@ -110,8 +110,9 @@ let cssVarsObserver = null;
  * @param {function} [options.onComplete] Callback after all CSS has been
  *                   processed, legacy-compatible CSS has been generated, and
  *                   (optionally) the DOM has been updated. Passes 1) a CSS
- *                   string with CSS variable values resolved, and 2) a
- *                   reference to the appended <style> node.
+ *                   string with CSS variable values resolved, 2) a reference to
+ *                   the appended <style> node, and 3) an object containing all
+ *                   custom properies names and values.
  *
  * @example
  *
Added JSDoc comments for options.onComplete