diff --git a/config/defaults.inc.php b/config/defaults.inc.php
index 29cc06900..268bf009a 100644
--- a/config/defaults.inc.php
+++ b/config/defaults.inc.php
@@ -975,7 +975,7 @@ $config['default_font'] = 'Verdana';
 
 // Default font size for composed HTML message.
 // Supported sizes: 8pt, 10pt, 12pt, 14pt, 18pt, 24pt, 36pt
-$rcmail_config['default_font_size'] = '10pt';
+$config['default_font_size'] = '10pt';
 
 // Enables display of email address with name instead of a name (and address in title)
 $config['message_show_email'] = false;