diff --git a/reference/var/functions/unserialize.xml b/reference/var/functions/unserialize.xml
index bad0202622..843a38d2dc 100644
--- a/reference/var/functions/unserialize.xml
+++ b/reference/var/functions/unserialize.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.7 $ -->
+<!-- $Revision: 1.8 $ -->
 <!-- splitted from ./en/functions/var.xml, last change in rev 1.2 -->
   <refentry id="function.unserialize">
    <refnamediv>
@@ -26,7 +26,7 @@
     <note>
      <title>unserialize_callback_func directive</title>
      <para>
-      It's possible to set a callback-function which will be called,
+      (PHP >= 4.2.0) It's possible to set a callback-function which will be called,
       if an undefined class should be instantiated during unserializing.
       (to prevent getting an incomplete <type>object</type> "__PHP_Incomplete_Class".)
       Use your &php.ini;, <function>ini_set</function> or .htaccess-file