Index: wp-includes/class-wp.php
===================================================================
--- wp-includes/class-wp.php	(revision 18589)
+++ wp-includes/class-wp.php	(working copy)
@@ -476,7 +476,7 @@
 
 		if ( !is_admin() && ( 0 == count( $wp_query->posts ) ) && !is_404() && !is_robots() && !is_search() && !is_home() ) {
 			// Don't 404 for these queries if they matched an object.
-			if ( ( is_tag() || is_category() || is_tax() || is_author() || is_post_type_archive() ) && $wp_query->get_queried_object() && !is_paged() ) {
+			if ( ( ( is_tag() || is_category() || is_tax() || is_author() || is_post_type_archive() ) && $wp_query->get_queried_object() && !is_paged() ) || is_feed() ) {
 				if ( !is_404() )
 					status_header( 200 );
 				return;