diff --git a/src/wp-admin/includes/media.php b/src/wp-admin/includes/media.php
index 904cbb0ebb..e259766d8b 100644
--- a/src/wp-admin/includes/media.php
+++ b/src/wp-admin/includes/media.php
@@ -112,7 +112,8 @@ function the_media_upload_tabs() {
  * @param string  $align   image css alignment property
  * @param string  $url     image src url
  * @param string  $rel     image rel attribute
- * @param string  $size    image size (thumbnail, medium, large, full or added  with add_image_size() )
+ * @param string|array $size Optional. Image size. Accepts any valid image size, or an array of width
+ *                           and height values in pixels (in that order).
  * @return string the html to insert into editor
  */
 function get_image_send_to_editor( $id, $caption, $title, $align, $url='', $rel = '', $size='medium', $alt = '' ) {