psql uses default user from kerberos ticket not the current user

Hi,

I have postgreslq 8.3.7. I have the following issue:

$ psql databasename
psql: FATAL:  role "litvinse" does not exist

If found the workaround:

$ kdestroy
$ psql databasename
Welcome to psql 8.3.7, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help with psql commands
       \g or terminate with semicolon to execute query
       \q to quit

databasename=#

Apparently default user is extracted from kerberos ticket. Is it possible
to disable this behavior and take current unix user as default user.

I would like to explicitly specify the username to psql and not to execute
kdestroy.

thank you,
--
Dmitry Litvintsev