Index: wp-includes/comment.php
===================================================================
--- wp-includes/comment.php	(revision 4262)
+++ wp-includes/comment.php	(working copy)
@@ -5,7 +5,7 @@
 
 	if (1 == get_option('comment_moderation')) return false; // If moderation is set to manual
 
-	if ( (count(explode('http:', $comment)) - 1) >= get_option('comment_max_links') )
+	if ( preg_match_all("|(href\t*?=\t*?['\"]?)?(https?:)?\/\/|", $comment, $out) >= get_option('comment_max_links') )
 		return false; // Check # of external links
 
 	$mod_keys = trim( get_option('moderation_keys') );