Make XML::XPath bypass DTD?

I'm using XML::XPath in the obvious way, along the lines of

my $xp = XML::XPath->new(filename => $ARGV[0]);

and the silly file has <!DOCTYPE foo SYSTEM "./foo.dtd">

I don't want it to validate and in fact I don't want it to read 
foo.dtd.  I can achieve this by doing "cp /dev/null foo.dtd" but is 
there a way to tell whatever machinery underlies XML::XPath to just 
ignore the <!DOCTYPE>? -Tim