diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 6098f6b020..381d8636ab 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1893,6 +1893,12 @@ include_dir 'conf.d'
         too high.  It may be useful to control for this by separately
         setting <xref linkend="guc-autovacuum-work-mem"/>.
        </para>
+       <para>
+        Additionally, <command>VACUUM</command> is only able to utilize up to
+        a maximum of <literal>1GB</literal> of memory, so
+        <varname>maintenance_work_mem</varname> values higher than this have
+        no effect on <command>VACUUM</command>.
+       </para>
       </listitem>
      </varlistentry>