\k Escape - Regex Perl

  
[CODE]
use Regexp::Keep;

my $s = "Gurpreet.Singh";
$s =~ s/.*\K\..*//;
print $s;
[/CODE]

throws a warning:

"Unrecognized escape \K passed through at [FileName].pl line 12."

What is this warning? When I googled or checked in CPAN, I got an answere: 
[Qoute]
*If* you're using this module, you don't have a version of Perl with the \K escape built-in
[/Qoute]

How do I determine whether \K escape is built-in my Perl or not? If not, how to make it compatible for that?

Thanks,
BR,
GSS

P.S. I have installed the Regex::Keep module.