diff --git a/reference/http/functions/header.xml b/reference/http/functions/header.xml
index 5202c3e7a1..c8e2f4c5f2 100644
--- a/reference/http/functions/header.xml
+++ b/reference/http/functions/header.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.4 $ -->
+<!-- $Revision: 1.5 $ -->
 <!-- splitted from ./en/functions/http.xml, last change in rev 1.2 -->
   <refentry id="function.header">
    <refnamediv>
@@ -37,7 +37,8 @@ header('WWW-Authenticate: NTLM', FALSE);
     </para>
     <para>
      The second optional <parameter>http_response_code</parameter> force the
-     HTTP response code to the specified value.
+     HTTP response code to the specified value. (This parameter is available
+     in PHP 4.3.0 and higher.)
     </para>
     <para>
      There are two special-case header calls.  The first is a header