diff --git a/appendices/migration53.xml b/appendices/migration53.xml
index d8522f057d..e8f42e4255 100644
--- a/appendices/migration53.xml
+++ b/appendices/migration53.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.27 $ -->
+<!-- $Revision: 1.28 $ -->
 <appendix xml:id="migration53" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
  <title>Migrating from PHP 5.2.x to PHP 5.3.x</title>
  <simpara>
@@ -2373,7 +2373,8 @@
     <simpara>
      <function>fopen</function> has a new mode option (<literal>n</literal>),
      which passes <constant>O_NONBLOCK</constant> to the underlying
-     <literal>open()</literal> system call.
+     <literal>open()</literal> system call. Note that this mode is not currently 
+     supported on Windows.
     </simpara>
    </listitem>
    <listitem>