diff --git a/wp-includes/post.php b/wp-includes/post.php
index b58b7d72d4..6e7870ba5e 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -452,6 +452,7 @@ function create_initial_post_types() {
 			'label'        => __( 'Global Styles' ),
 			'description'  => 'CPT to store user design tokens',
 			'public'       => false,
+			'_builtin'     => true, /* internal use only. don't use this when registering your own post type. */
 			'show_ui'      => false,
 			'show_in_rest' => false,
 			'rewrite'      => false,
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2681ee3622..16c91908c9 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-52107';
+$wp_version = '5.9-alpha-52108';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.