diff --git wp-includes/widgets.php wp-includes/widgets.php
index fbbdcf5..0141eee 100644
--- wp-includes/widgets.php
+++ wp-includes/widgets.php
@@ -613,6 +613,8 @@ function wp_unregister_widget_control($id) {
 function dynamic_sidebar( $index = 1 ) {
 	global $wp_registered_sidebars, $wp_registered_widgets;
 
+	$index = apply_filters( 'dynamic_sidebar_index', $index );
+
 	if ( is_int( $index ) ) {
 		$index = "sidebar-$index";
 	} else {