diff --git a/phpBB/includes/functions_post.php b/phpBB/includes/functions_post.php
index b5ae99d289..d4cf5ae483 100644
--- a/phpBB/includes/functions_post.php
+++ b/phpBB/includes/functions_post.php
@@ -72,9 +72,9 @@ function prepare_message($message, $html_on, $bbcode_on, $smile_on, $bbcode_uid
 				for ($i = 0; $i < sizeof($allowed_html_tags); $i++)
 				{
 					$match_tag = trim($allowed_html_tags[$i]);
-					if (preg_match('#^<\/?' . $match_tag . '(?!(.*?)((style)|( on[\w]+?[\s]?=))[\s]*?)#i', $hold_string))
+					if (preg_match('#^<\/?' . $match_tag . '[> ]#i', $hold_string))
 					{
-						$tagallowed = true;
+						$tagallowed = (preg_match('#^<\/?' . $match_tag . ' .*?(style[ ]*?=|on[\w]+[ ]*?=)#i', $hold_string)) ? false : true;
 					}
 				}