diff --git a/chapter05/gcc-pass1.xml b/chapter05/gcc-pass1.xml
index 23c7fe7e8..af09946d7 100644
--- a/chapter05/gcc-pass1.xml
+++ b/chapter05/gcc-pass1.xml
@@ -222,6 +222,14 @@ cd ../gcc-build</userinput></screen>
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><parameter>--with-mpfr-*</parameter></term>
+        <listitem>
+          <para>These options enable the build system to correctly use the
+          in-tree copy of the MPFR sources.</para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
 
     <para>Compile GCC by running:</para>