diff --git a/wp-includes/post.php b/wp-includes/post.php
index 25fefbb621..69a6362552 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -6665,9 +6665,9 @@ function wp_get_attachment_thumb_url( $post_id = 0 ) {
  *
  * @since 4.2.0
  *
- * @param string      $type Attachment type. Accepts 'image', 'audio', or 'video'.
+ * @param string      $type Attachment type. Accepts `image`, `audio`, `video`, or a file extension.
  * @param int|WP_Post $post Optional. Attachment ID or object. Default is global $post.
- * @return bool True if one of the accepted types, false otherwise.
+ * @return bool True if an accepted type or a matching file extension, false otherwise.
  */
 function wp_attachment_is( $type, $post = null ) {
 	$post = get_post( $post );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 6b40365fde..f455373ad8 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.5-alpha-57272';
+$wp_version = '6.5-alpha-57273';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.