create extension failed

Hello.
I have one test database, which was upgraded from 8.4 to 9.0. Now I've  
upgraded it to 9.1. I'm trying to create extension for hstore.

db=# CREATE EXTENSION hstore WITH SCHEMA public FROM unpackaged;
ERROR:  function hstore_recv(internal) does not exist

I suppose, that hstore_recv was added in 9.0, but I didn't update  
hstore extension after upgrading from 8.4 to 9.0. Is this assumption  
correct? How am I supposed to deal with this situation?

Finally, I was able to create extension after the following:
sed -e 's|MODULE_PATHNAME|$libdir/hstore|' <  
/usr/local/share/postgresql/extension/hstore--1.0.sql | su pgsql -c  
'psql -d db '
db=# CREATE EXTENSION hstore WITH SCHEMA public FROM unpackaged;

I'm not sure if it was a right thing...

-- 
С уважением,
Александр Пыхалов,
системный администратор ЮГИНФО ЮФУ