diff --git a/phpBB/viewtopic.php b/phpBB/viewtopic.php
index 80ba4d8a54..53da7f539f 100644
--- a/phpBB/viewtopic.php
+++ b/phpBB/viewtopic.php
@@ -1157,7 +1157,7 @@ while ($row = $db->sql_fetchrow($result))
 
 			if (!empty($row['user_icq']))
 			{
-				$user_cache[$poster_id]['icq'] = 'http://www.icq.com/people/' . $row['user_icq'] . '/';
+				$user_cache[$poster_id]['icq'] = 'http://www.icq.com/people/' . urlencode($row['user_icq']) . '/';
 				$user_cache[$poster_id]['icq_status_img'] = '<img src="http://web.icq.com/whitepages/online?icq=' . $row['user_icq'] . '&amp;img=5" width="18" height="18" alt="" />';
 			}
 			else