diff --git a/wp-includes/default-widgets.php b/wp-includes/default-widgets.php
index 8a803a4770..97532c1eef 100644
--- a/wp-includes/default-widgets.php
+++ b/wp-includes/default-widgets.php
@@ -732,7 +732,7 @@ class WP_Widget_Recent_Posts extends WP_Widget {
 			$cache[ $args['widget_id'] ] = ob_get_flush();
 			wp_cache_set( 'widget_recent_posts', $cache, 'widget' );
 		} else {
-			ob_flush();
+			ob_end_flush();
 		}
 	}