diff --git a/reference/mbstring/reference.xml b/reference/mbstring/reference.xml
index d10be68371..ddd3852bcd 100644
--- a/reference/mbstring/reference.xml
+++ b/reference/mbstring/reference.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.3 $ -->
+<!-- $Revision: 1.4 $ -->
  <reference id="ref.mbstring">
   <title>Multi-Byte String Functions</title> 
   <titleabbrev>Multi-Byte String</titleabbrev>
@@ -126,6 +126,12 @@ JIS, SJIS
          automatically.
         </para>
        </listitem>
+       <listitem>
+        <para>
+         <option role="configure">--enable-mbregex</option> : Enable
+         regular expression functions with multibyte character support.
+        </para>
+       </listitem>
       </itemizedlist>
      </para>
    </section>