diff --git a/reference/imagick/imagick/setimagematte.xml b/reference/imagick/imagick/setimagematte.xml
index dba5c8db9a..f09060c640 100644
--- a/reference/imagick/imagick/setimagematte.xml
+++ b/reference/imagick/imagick/setimagematte.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.6 $ -->
+<!-- $Revision: 1.7 $ -->
 <refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.imagick-setimagematte">
  <refnamediv>
   <refname>Imagick::setImageMatte</refname>
@@ -12,9 +12,10 @@
    <type>bool</type><methodname>Imagick::setImageMatte</methodname>
    <methodparam><type>bool</type><parameter>matte</parameter></methodparam>
   </methodsynopsis>
-  &warn.undocumented.func;
+
   <para>
-   Sets the image matte channel.
+   Sets the image matte channel. This method is available if 
+   Imagick has been compiled against ImageMagick version 6.2.9 or newer.
   </para>
  </refsect1>
 
@@ -26,6 +27,7 @@
      <term><parameter>matte</parameter></term>
      <listitem>
       <para>
+       True activates the matte channel and false disables it.
       </para>
      </listitem>
     </varlistentry>