diff --git a/packages/gatsby/src/redux/actions.js b/packages/gatsby/src/redux/actions.js
index a1e616ef0295f..073cb18032b84 100644
--- a/packages/gatsby/src/redux/actions.js
+++ b/packages/gatsby/src/redux/actions.js
@@ -85,6 +85,8 @@ const pascalCase = _.flow(_.camelCase, _.upperFirst)
  * @param {Object} page a page object
  * @param {string} page.path Any valid URL. Must start with a forward slash
  * @param {string} page.component The absolute path to the component for this page
+ * @param {string} page.layout The name of the layout for this page. By default
+ * `'index'` layout is used
  * @param {Object} page.context Context data for this page. Passed as props
  * to the component `this.props.pathContext` as well as to the graphql query
  * as graphql arguments.