diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
new file mode 100644
index ce5e308..e97fb48
*** a/doc/src/sgml/ref/pgupgrade.sgml
--- b/doc/src/sgml/ref/pgupgrade.sgml
*************** make prefix=/usr/local/pgsql.new install
*** 274,279 ****
--- 274,281 ----
       whether they are from <filename>contrib</filename>
       or some other source. Do not install the schema definitions, e.g.
       <filename>pgcrypto.sql</>, because these will be upgraded from the old cluster.
+      Also, any custom full text search files (dictionary, synonym,
+      thesaurus, stop words) must also be copied to the new cluster.
      </para>
     </step>