DBI:Sybase - Period in database name

[apu]

Using DBI:Sybase to connect to an MS SQL Server. The database is the backend of a commercial inventory management system and I need to get some data out of it, massage it and generate some formatted output. My problem is that the database I need has a period in its name and, I think, DBI is interpreting this a separate between a database name and a table name. There is another database on the same server, generated by the same commercial program, named ps_inventory (without the ".ad") and I can connect to and query it without a problem.

my $DBNAME = 'ps_inventory.ad';
...
$dbh->do("use $DBNAME");

How do I escape the period? I tried quotes, backticks, a backslash, ... nothing seems to work Thanks in advance, Monks.