diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index a83c63cd98..5ab7c57cd9 100644
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -299,15 +299,17 @@ make prefix=/usr/local/pgsql.new install
    </step>
 
    <step>
-    <title>Install custom shared object files</title>
+    <title>Install extension shared object files</title>
 
     <para>
-     Install any custom shared object files (or DLLs) used by the old cluster
-     into the new cluster, e.g., <filename>pgcrypto.so</filename>,
-     whether they are from <filename>contrib</filename>
-     or some other source. Do not install the schema definitions, e.g.,
-     <command>CREATE EXTENSION pgcrypto</command>, because these will be upgraded
-     from the old cluster.
+     If the old cluster used extensions, whether from
+     <filename>contrib</filename> or some other source, install new
+     versions of the extension shared object files (or DLLs) into the
+     new cluster, e.g., <filename>pgcrypto.so</filename>.
+     Do not load the schema definitions, e.g.,
+     <command>CREATE EXTENSION pgcrypto</command>, because these will be
+     recreated from the old cluster.  (The extensions may be
+     upgraded later using <literal>ALTER EXTENSION ... UPGRADE</literal>.)
      Also, any custom full text search files (dictionary, synonym,
      thesaurus, stop words) must also be copied to the new cluster.
     </para>
@@ -494,10 +496,10 @@ pg_upgrade.exe
      </step>
 
      <step>
-      <title>Install custom shared object files</title>
+      <title>Install extension shared object files</title>
 
       <para>
-       Install the same custom shared object files on the new standbys
+       Install the same extension shared object files on the new standbys
        that you installed in the new primary cluster.
       </para>
      </step>