diff --git a/reference/apache/functions/virtual.xml b/reference/apache/functions/virtual.xml
index 78af083985..f4dc2a69d6 100644
--- a/reference/apache/functions/virtual.xml
+++ b/reference/apache/functions/virtual.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.7 $ -->
+<!-- $Revision: 1.8 $ -->
 <!-- splitted from ./en/functions/apache.xml, last change in rev 1.20 -->
   <refentry id="function.virtual">
    <refnamediv>
@@ -25,6 +25,15 @@
      To run the sub-request, all buffers are terminated and flushed to the
      browser, pending headers are sent too.
     </para>
+    <warning>
+     <para>
+      This function works only when PHP is compiled as an Apache module,
+      since it uses the Apache API for doing sub requests. Query string can be
+      passed to the included file but <varname>$_GET</varname> is copied from
+      the parent script and only <varname>$_SERVER['QUERY_STRING']</varname> is
+      filled by the passed query string.
+     </para>
+    </warning>
     <para>
      As of PHP 4.0.6, you can use <function>virtual</function> on PHP files.
      However, it is typically better to use <function>include</function> or