diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index bf1eecbb7a..01c775a4e6 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -141,6 +141,7 @@ h3 {font-size:12pt;color:blue}
 <li>Fixed some problems with gzip in combination with newer PHP versions and Mozilla</li>
 <li>Fixed wrong maxlength in modcp_split.tpl subject field</li>
 <li>Fixed inability to edit username of guest poster - <b>vHiker</b></li>
+<li>Fixed ability for guests to post with certain registered usernames</li>
 <li></li>
 </ul>
 
diff --git a/phpBB/includes/functions_post.php b/phpBB/includes/functions_post.php
index e496395a4a..2c6f0c7b35 100644
--- a/phpBB/includes/functions_post.php
+++ b/phpBB/includes/functions_post.php
@@ -150,7 +150,7 @@ function prepare_post(&$mode, &$post_data, &$bbcode_on, &$html_on, &$smilies_on,
 	// Check username
 	if ( !empty($username) )
 	{
-		$username = htmlspecialchars(trim(strip_tags($username)));
+		$username = trim(strip_tags($username));
 
 		if ( !$userdata['session_logged_in'] || ( $userdata['session_logged_in'] && $username != $userdata['username'] ) )
 		{
@@ -162,6 +162,10 @@ function prepare_post(&$mode, &$post_data, &$bbcode_on, &$html_on, &$smilies_on,
 				$error_msg .= ( !empty($error_msg) ) ? '<br />' . $result['error_msg'] : $result['error_msg'];
 			}
 		}
+		else
+		{
+			$username = '';
+		}
 	}
 
 	// Check subject