diff --git a/doc/src/sgml/docguide.sgml b/doc/src/sgml/docguide.sgml
index 17d36e9145..66a1951c5e 100644
--- a/doc/src/sgml/docguide.sgml
+++ b/doc/src/sgml/docguide.sgml
@@ -234,15 +234,31 @@ brew install docbook docbook-xsl fop
    like this:
 <screen>
 checking for xmllint... xmllint
-checking for DocBook XML V4.5... yes
 checking for dbtoepub... dbtoepub
 checking for xsltproc... xsltproc
 checking for fop... fop
 </screen>
-   If <filename>xmllint</filename> was not found then some of the following
-   tests will be skipped.
+   If <filename>xmllint</filename> or <filename>xsltproc</filename> is not
+   found, you will not be able to build any of the documentation.
+   <filename>fop</filename> is only needed to build the documentation in
+   PDF format.
+   <filename>dbtoepub</filename> is only needed to build the documentation
+   in EPUB format.
   </para>
 
+  <para>
+   If necessary, you can tell <filename>configure</filename> where to find
+   these programs, for example
+<screen>
+./configure ... XMLLINT=/opt/local/bin/xmllint ...
+</screen>
+   Also, if you want to ensure that <filename>xmllint</filename>
+   and <filename>xsltproc</filename> will not perform any network access,
+   you can do something like
+<screen>
+./configure ... XMLLINT="xmllint --nonet" XSLTPROC="xsltproc --nonet" ...
+</screen>
+  </para>
   </sect2>
  </sect1>