diff --git a/doc/src/sgml/pgupgrade.sgml b/doc/src/sgml/pgupgrade.sgml
new file mode 100644
index 9e43f3c..301222c
*** a/doc/src/sgml/pgupgrade.sgml
--- b/doc/src/sgml/pgupgrade.sgml
*************** psql --username postgres --file script.s
*** 520,530 ****
    </para>
  
    <para>
!    If doing <option>--check</> with a running old server of a pre-9.1 version,
!    and the old server is using a Unix-domain socket directory that is
!    different from the default built into the new <productname>PostgreSQL</>
!    installation, set <envar>PGHOST</> to point to the socket location of the
!    old server.  (This is not relevant on Windows.)
    </para>
  
    <para>
--- 520,529 ----
    </para>
  
    <para>
!    If using a pre-9.1 old server that is using a non-default Unix-domain
!    socket directory or a default that differs from the default of the
!    new cluster, set <envar>PGHOST</> to point to the old server's socket
!    location.  (This is not relevant on Windows.)
    </para>
  
    <para>