diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index f82f08d29e37..8a77a441b302 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -34,6 +34,17 @@
 /** WordPress Styles Functions */
 require ABSPATH . WPINC . '/functions.wp-styles.php';
 
+/**
+ * get_stylsheet_directory is used by
+ * WP_Theme_JSON_Resolver::theme_has_support()
+ */
+if ( ! function_exists( 'get_stylesheet_directory' ) ) {
+	require_once ABSPATH . WPINC . '/theme.php';
+}
+if ( ! class_exists( 'WP_Theme_JSON_Resolver' ) ) {
+	require_once ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
+}
+
 /**
  * Registers TinyMCE scripts.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 628311e769cd..882ec44bb102 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-51000';
+$wp_version = '5.8-alpha-51001';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-settings.php b/wp-settings.php
index 770fa9ff3dce..47dad42e20aa 100644
--- a/wp-settings.php
+++ b/wp-settings.php
@@ -299,7 +299,7 @@
 require ABSPATH . WPINC . '/blocks.php';
 require ABSPATH . WPINC . '/blocks/index.php';
 require ABSPATH . WPINC . '/class-wp-theme-json.php';
-require ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
+require_once ABSPATH . WPINC . '/class-wp-theme-json-resolver.php';
 require ABSPATH . WPINC . '/block-editor.php';
 require ABSPATH . WPINC . '/block-patterns.php';
 require ABSPATH . WPINC . '/class-wp-block-supports.php';