FATAL: role "postgres" does not exist

Hi all,
Back again with another FreeBSD 'centric question.  I'm running the OpenNMS installer which "configures PostgreSQL
tables,users, and other miscellaneous settings." 

It bombs with this:

Exception in thread "main" org.postgresql.util.PSQLException: Backend start-up failed:
org.postgresql.util.PSQLException:FATAL: role "postgres" does not exist 

I don't know what it's looking for.  When you install the server from ports, it creates the user "pgsql" in
/etc/passwd.  

How do I get the "role" postgres?  Is that a role in Postgresql that I need to create?

opennms# sh install -disU
==============================================================================
OpenNMS Installer Version $Id: Installer.java 3056 2006-03-26 19:39:16Z djgregor $
==============================================================================

Configures PostgreSQL tables, users, and other miscellaneous settings.

Exception in thread "main" org.postgresql.util.PSQLException: Backend start-up failed:
org.postgresql.util.PSQLException:FATAL: role "postgres" does not exist 

        at org.postgresql.jdbc1.AbstractJdbc1Connection.openConnectionV3(AbstractJdbc1Connection.java:460)
        at org.postgresql.jdbc1.AbstractJdbc1Connection.openConnection(AbstractJdbc1Connection.java:214)
        at org.postgresql.Driver.connect(Driver.java:139)
        at java.sql.DriverManager.getConnection(DriverManager.java:512)
        at java.sql.DriverManager.getConnection(DriverManager.java:171)
        at org.opennms.install.Installer.databaseConnect(Installer.java:613)
        at org.opennms.install.Installer.install(Installer.java:195)
        at org.opennms.install.Installer.main(Installer.java:2450)


Any suggestions?

Thanks,
Bob