Index: wp-comments-post.php
===================================================================
--- wp-comments-post.php	(revision 24705)
+++ wp-comments-post.php	(working copy)
@@ -60,8 +60,8 @@
 	$comment_author       = $wpdb->escape($user->display_name);
 	$comment_author_email = $wpdb->escape($user->user_email);
 	$comment_author_url   = $wpdb->escape($user->user_url);
-	if ( current_user_can('unfiltered_html') ) {
-		if ( wp_create_nonce('unfiltered-html-comment_' . $comment_post_ID) != $_POST['_wp_unfiltered_html_comment'] ) {
+	if ( current_user_can( 'unfiltered_html' ) && isset( $_POST['_wp_unfiltered_html_comment'] ) ) {
+		if ( wp_create_nonce( 'unfiltered-html-comment_' . $comment_post_ID ) != $_POST['_wp_unfiltered_html_comment'] ) {
 			kses_remove_filters(); // start with a clean slate
 			kses_init_filters(); // set up the filters
 		}