diff --git a/reference/yaf/yaf-config-ini.xml b/reference/yaf/yaf-config-ini.xml
index 13829173d9..3516cbb400 100644
--- a/reference/yaf/yaf-config-ini.xml
+++ b/reference/yaf/yaf-config-ini.xml
@@ -26,7 +26,7 @@
    Yaf_Config_Ini utilizes the » parse_ini_file() PHP function. Please review
    this documentation to be aware of its specific behaviors, which propagate
    to Yaf_Config_Ini, such as how the special values of "&true;", "&false;",
-   "yes", "no", and "NULL" are handled. 
+   "yes", "no", and "&null;" are handled. 
    </para>
   </note>
   </para>
diff --git a/reference/yaf/yaf_application/app.xml b/reference/yaf/yaf_application/app.xml
index fd7cb3c3ae..32ac1213a1 100644
--- a/reference/yaf/yaf_application/app.xml
+++ b/reference/yaf/yaf_application/app.xml
@@ -29,8 +29,8 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
-   an Yaf_Application instance, if no Yaf_Application initialized before, NULL
-   will be returned.
+   an Yaf_Application instance, if no Yaf_Application initialized before,
+   &null; will be returned.
   </para>
  </refsect1>
 
diff --git a/reference/yaf/yaf_response_abstract/getbody.xml b/reference/yaf/yaf_response_abstract/getbody.xml
index d99c032d6d..004a98a333 100644
--- a/reference/yaf/yaf_response_abstract/getbody.xml
+++ b/reference/yaf/yaf_response_abstract/getbody.xml
@@ -26,7 +26,7 @@
     <listitem>
      <para>
       the content key, if you don't specific, then Yaf_Response_Abstract::DEFAULT_BODY
-      will be used. if you pass in a NULL, then all contents will be returned
+      will be used. if you pass in a &null;, then all contents will be returned
       as a array
       <note>
        <para>
diff --git a/reference/yaf/yaf_router/getcurrentroute.xml b/reference/yaf/yaf_router/getcurrentroute.xml
index f7aa0ccf56..c441fd2d25 100644
--- a/reference/yaf/yaf_router/getcurrentroute.xml
+++ b/reference/yaf/yaf_router/getcurrentroute.xml
@@ -18,7 +18,7 @@
    <note>
     <para>
      You should call this method after the route process finished, since
-     before that, this method will always return NULL.
+     before that, this method will always return &null;.
     </para>
    </note>
   </para>