Index: wp-includes/comment-template.php
===================================================================
--- wp-includes/comment-template.php	(revision 15432)
+++ wp-includes/comment-template.php	(working copy)
@@ -917,7 +917,7 @@
 	elseif ( file_exists( TEMPLATEPATH . $file ) )
 		require( TEMPLATEPATH .  $file );
 	else // Backward compat code will be removed in a future release
-		require( WPINC . '/theme-compat/comments.php');
+		require( ABSPATH . WPINC . '/theme-compat/comments.php');
 }
 
 /**