diff --git a/phpgwapi/inc/class.html.inc.php b/phpgwapi/inc/class.html.inc.php
index 17cb85f3c6..43a8d5361a 100644
--- a/phpgwapi/inc/class.html.inc.php
+++ b/phpgwapi/inc/class.html.inc.php
@@ -205,7 +205,7 @@ class html
// actual allowed tags and attributes
$config->set('URI.AllowedSchemes', array('http'=>true, 'https'=>true, 'ftp'=>true, 'file'=>true, 'cid'=>true));
$config->set('AutoFormat.RemoveEmpty', true);
- $config->set('HTML.Allowed', 'br,p[align],b,i,u,s,em,pre,tt,strong,strike,center,div[align|style],hr[class|style],'.
+ $config->set('HTML.Allowed', 'br,p[align],b,i,u,s,em,pre,tt,strong,strike,sub,sup,center,div[align|style],hr[class|style],'.
'font[size|color],'.
'ul[type],ol[type|start],li,'.
'h1,h2,h3,h4,h5,h6,'.
@@ -248,7 +248,7 @@ class html
// actual allowed tags and attributes
$config->set('URI.AllowedSchemes', array('http'=>true, 'https'=>true, 'ftp'=>true, 'file'=>true, 'cid'=>true));
$config->set('AutoFormat.RemoveEmpty', true);
- $config->set('HTML.Allowed', 'br,p[align],b,i,u,s,em,pre,tt,strong,strike,center,div[align|style],hr[class|style],'.
+ $config->set('HTML.Allowed', 'br,p[align],b,i,u,s,em,pre,tt,strong,strike,sub,sup,center,div[align|style],hr[class|style],'.
'font[size|color],'.
'ul[type],ol[type|start],li,'.
'h1,h2,h3,h4,h5,h6,'.
@@ -1421,7 +1421,7 @@ class html
// enable target attributes
$config->set('Attr.AllowedFrameTargets','_blank,_top,_self,_parent');
// actual allowed tags and attributes
- $config->set('HTML.Allowed', 'br,p[align|style],b,i,u,s,em,pre,tt,strong,strike,center,div[align|style],hr[class|style],'.
+ $config->set('HTML.Allowed', 'br,p[align|style],b,i,u,s,em,pre,tt,strong,strike,sub,sup,center,div[align|style],hr[class|style],'.
'ul[type],ol[type|start],li,'.
'h1,h2,h3,h4,h5,h6,'.
'span[class|style],'.