diff --git a/expat/doc/xmlwf.xml b/expat/doc/xmlwf.xml
index 38934b11..b2ca99cd 100644
--- a/expat/doc/xmlwf.xml
+++ b/expat/doc/xmlwf.xml
@@ -257,6 +257,17 @@ supports both.
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>-g</option> <replaceable>bytes</replaceable></term>
+        <listitem>
+          <para>
+            Sets the buffer size to request per call pair to
+            <function>XML_GetBuffer</function> and <function>read</function>
+            (default: 8 KiB).
+          </para>
+        </listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>-h</option></term>
         <term><option>--help</option></term>