diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index d5f4f0e0ba..37930194ea 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -1205,7 +1205,7 @@ function register_post_type( $post_type, $args = array() ) {
  * @global array      $wp_post_types          List of post types.
  *
  * @param string $post_type Post type to unregister.
- * @return bool|WP_Error True on success, WP_Error on failure.
+ * @return bool|WP_Error True on success, WP_Error on failure or if the post type doesn't exist.
  */
 function unregister_post_type( $post_type ) {
 	if ( ! post_type_exists( $post_type ) ) {