diff --git a/reference/apache/functions/apache-setenv.xml b/reference/apache/functions/apache-setenv.xml
index f526afee62..3b55681897 100644
--- a/reference/apache/functions/apache-setenv.xml
+++ b/reference/apache/functions/apache-setenv.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.6 $ -->
+<!-- $Revision: 1.7 $ -->
 <!-- splitted from ./en/functions/apache.xml, last change in rev 1.7 -->
 <refentry id="function.apache-setenv">
  <refnamediv>
@@ -20,6 +20,9 @@
    environment variable specified by
    <parameter>variable</parameter>.
   </para>
+  <para>
+   This function requires Apache 2 otherwise it's undefined.
+  </para>
   <note>
    <para>
     When setting an Apache environment variable, the corresponding