diff --git a/wp-includes/js/customize-base.js b/wp-includes/js/customize-base.js
index 8fd247052c..e6aeb8b641 100644
--- a/wp-includes/js/customize-base.js
+++ b/wp-includes/js/customize-base.js
@@ -112,8 +112,8 @@ window.wp = window.wp || {};
 	 * @param object staticProps Properties to apply directly to the class.
 	 * @return child The subclass.
 	 */
-	api.Class.extend = function( protoProps, classProps ) {
-		var child = inherits( this, protoProps, classProps );
+	api.Class.extend = function( protoProps, staticProps ) {
+		var child = inherits( this, protoProps, staticProps );
 		child.extend = this.extend;
 		return child;
 	};
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 831f710396..f835bc6da7 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.6-beta2-49352';
+$wp_version = '5.6-beta2-49353';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.