Ticket #11878: 11878.patch

post-template.php

@@ -306 +306 @@
 function get_post_class( $class = '', $post_id = null ) {
         $post = get_post($post_id);
 
+        if(is_null($post_id))
+                $post_id = $post->ID;
+        
         $classes = array();
 
         if ( empty($post) )