diff --git a/src/wp-includes/class-wp-customize-manager.php b/src/wp-includes/class-wp-customize-manager.php
index 79f2b3eab3..58905d6822 100644
--- a/src/wp-includes/class-wp-customize-manager.php
+++ b/src/wp-includes/class-wp-customize-manager.php
@@ -1231,6 +1231,8 @@ final class WP_Customize_Manager {
 						$settings = $settings->getArrayCopy();
 					}
 
+					unset( $settings['_multiwidget'] );
+
 					// Find the max widget number for this type.
 					$widget_numbers = array_keys( $settings );
 					if ( count( $widget_numbers ) > 0 ) {