diff --git a/reference/phar/functions/phar-cancompress.xml b/reference/phar/functions/phar-cancompress.xml
index f20bda4e23..a928706488 100644
--- a/reference/phar/functions/phar-cancompress.xml
+++ b/reference/phar/functions/phar-cancompress.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.2 $ -->
+<!-- $Revision: 1.3 $ -->
 <refentry id="function.phar-cancompress">
  <refnamediv>
   <refname>Phar::canCompress</refname>
@@ -9,18 +9,30 @@
   &reftitle.description;
   <methodsynopsis>
    <type>bool</type><methodname>Phar::canCompress</methodname>
-   <void/>
+   <methodparam choice="opt"><type>int</type><parameter>type</parameter></methodparam>
   </methodsynopsis>
 
   <para>
    This should be used to test whether compression is possible prior to
    loading a phar archive containing compressed files.
   </para>
-
  </refsect1>
+
  <refsect1 role="parameters">
   &reftitle.parameters;
   <para>
+   <variablelist>
+    <varlistentry>
+     <term><parameter>type</parameter></term>
+     <listitem>
+      <para>
+       Either <literal>Phar::GZ</literal> or <literal>Phar::BZ2</literal> can be
+       used to test whether compression is possible with a specific compression
+       algorithm (zlib or bzip2).
+      </para>
+     </listitem>
+    </varlistentry>
+   </variablelist>
   </para>
  </refsect1>
  <refsect1 role="returnvalues">