diff --git a/wp-includes/class-wp-editor.php b/wp-includes/class-wp-editor.php
index 9ec353c907..5387d850d5 100644
--- a/wp-includes/class-wp-editor.php
+++ b/wp-includes/class-wp-editor.php
@@ -969,8 +969,12 @@ final class _WP_Editors {
 		?>
 		<script type="text/javascript">
 		window.wp = window.wp || {};
-		window.wp.editor = window.wp.oldEditor = window.wp.oldEditor || {};
-		window.wp.oldEditor.getDefaultSettings = function() {
+		window.wp.editor = window.wp.editor || {};
+		window.wp.oldEditor = window.wp.oldEditor || {};
+
+		// Add getDefaultSettings() to both wp.editor and wp.oldEditor for back compat.
+		// Use of wp.editor for "old editor" functionality should be deprecated.
+		window.wp.editor.getDefaultSettings = window.wp.oldEditor.getDefaultSettings = function() {
 			return {
 				tinymce: <?php echo $settings; ?>,
 				quicktags: {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 4bd3d8fdbb..8cd901fcb0 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51740';
+$wp_version = '5.9-alpha-51748';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.