diff --git a/doc/src/sgml/release-10.sgml b/doc/src/sgml/release-10.sgml
index 968ed866c2..f1dc816278 100644
--- a/doc/src/sgml/release-10.sgml
+++ b/doc/src/sgml/release-10.sgml
@@ -4717,6 +4717,13 @@ Branch: REL_10_STABLE [5159626af] 2017-11-03 14:14:16 -0400
      </para>
 
      <para>
+      Also, sequences created for <literal>SERIAL</literal> columns now
+      generate positive 32-bit wide values rather than 64-bit, as they
+      used to.  (This has no visible effect if the values are just stored in
+      the column.)
+     </para>
+
+     <para>
       The output of <application>psql</application>'s <command>\d</command> command for a
       sequence has been redesigned, too.
      </para>