diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f0a50a5f9a..872dcdf325 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -659,7 +659,13 @@ include_dir 'conf.d'
          to it.
          The default value is <systemitem class="systemname">localhost</systemitem>,
          which allows only local TCP/IP <quote>loopback</quote> connections to be
-         made.  While client authentication (<xref
+         made.  If <varname>listen_addresses</varname> is not empty,
+         the server will start if it can open a <varname>port</varname>
+         on at least one TCP/IP address.  A warning will be emitted for
+         any TCP/IP address which cannot be opened.
+       </para>
+       <para>
+         While client authentication (<xref
          linkend="client-authentication"/>) allows fine-grained control
          over who can access the server, <varname>listen_addresses</varname>
          controls which interfaces accept connection attempts, which