Index: wp-includes/feed.php
===================================================================
--- wp-includes/feed.php	(revision 42547)
+++ wp-includes/feed.php	(working copy)
@@ -693,14 +693,10 @@
 
 	$feed = new SimplePie();
 
-	$feed->set_sanitize_class( 'WP_SimplePie_Sanitize_KSES' );
-	// We must manually overwrite $feed->sanitize because SimplePie's
-	// constructor sets it before we have a chance to set the sanitization class
-	$feed->sanitize = new WP_SimplePie_Sanitize_KSES();
+	$feed->registry->register( 'Sanitize', 'WP_SimplePie_Sanitize_KSES', true );
+	$feed->registry->register( 'Cache', 'WP_Feed_Cache', true );
+	$feed->registry->register( 'File', 'WP_SimplePie_File', true );
 
-	$feed->set_cache_class( 'WP_Feed_Cache' );
-	$feed->set_file_class( 'WP_SimplePie_File' );
-
 	$feed->set_feed_url( $url );
 	/** This filter is documented in wp-includes/class-wp-feed-cache-transient.php */
 	$feed->set_cache_duration( apply_filters( 'wp_feed_cache_transient_lifetime', 12 * HOUR_IN_SECONDS, $url ) );