diff --git a/reference/yaf/yaf-session.xml b/reference/yaf/yaf-session.xml
index aec2d0449d..541bc44f4e 100644
--- a/reference/yaf/yaf-session.xml
+++ b/reference/yaf/yaf-session.xml
@@ -49,6 +49,7 @@
 <!-- }}} -->
     <classsynopsisinfo role="comment">&Properties;</classsynopsisinfo>
     <fieldsynopsis>
+     <modifier>protected</modifier>
      <modifier>static</modifier>
      <varname linkend="yaf-session.props.instance">_instance</varname>
     </fieldsynopsis>