diff --git a/wp-includes/class-wp-customize-widgets.php b/wp-includes/class-wp-customize-widgets.php
index a180a93008..edfd3df81d 100644
--- a/wp-includes/class-wp-customize-widgets.php
+++ b/wp-includes/class-wp-customize-widgets.php
@@ -35,9 +35,23 @@ final class WP_Customize_Widgets {
 	 * @var array
 	 */
 	protected $core_widget_id_bases = array(
-		'archives', 'calendar', 'categories', 'links', 'meta',
-		'nav_menu', 'pages', 'recent-comments', 'recent-posts',
-		'rss', 'search', 'tag_cloud', 'text',
+		'archives',
+		'calendar',
+		'categories',
+		'custom_html',
+		'links',
+		'media_audio',
+		'media_image',
+		'media_video',
+		'meta',
+		'nav_menu',
+		'pages',
+		'recent-comments',
+		'recent-posts',
+		'rss',
+		'search',
+		'tag_cloud',
+		'text',
 	);
 
 	/**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index c321cb7f35..a8fd15621e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-40999';
+$wp_version = '4.9-alpha-41000';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/widgets/class-wp-widget-custom-html.php b/wp-includes/widgets/class-wp-widget-custom-html.php
index f6d28fd625..2db50f4d22 100644
--- a/wp-includes/widgets/class-wp-widget-custom-html.php
+++ b/wp-includes/widgets/class-wp-widget-custom-html.php
@@ -38,7 +38,10 @@ class WP_Widget_Custom_HTML extends WP_Widget {
 			'description' => __( 'Arbitrary HTML code.' ),
 			'customize_selective_refresh' => true,
 		);
-		$control_ops = array();
+		$control_ops = array(
+			'width' => 400,
+			'height' => 350,
+		);
 		parent::__construct( 'custom_html', __( 'Custom HTML' ), $widget_ops, $control_ops );
 	}