diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index d617ea41c..6b41f2ba5 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -173,8 +173,6 @@ function wp_allow_comment($commentdata) {
 	global $wpdb;
 	extract($commentdata);
 
-	$comment_user_domain = apply_filters('pre_comment_user_domain', gethostbyaddr($comment_author_IP) );
-
 	// Simple duplicate check
 	$dupe = "SELECT comment_ID FROM $wpdb->comments WHERE comment_post_ID = '$comment_post_ID' AND ( comment_author = '$comment_author' ";
 	if ( $comment_author_email )