Index: wp-includes/query.php
===================================================================
--- wp-includes/query.php	(revision 22210)
+++ wp-includes/query.php	(working copy)
@@ -2776,6 +2776,8 @@
 
 		// Always sanitize
 		foreach ( $this->posts as $i => $post ) {
+			if ( ! is_a( $post, 'WP_Post' ) )
+				$this->posts[$i] = new WP_Post( $post );
 			$this->posts[$i] = sanitize_post( $post, 'raw' );
 		}