Question: Poco::Glob::match()

[shailcompsit]

In my project I need to use Poco::Glob::match() on a const Glob pattern object.
e.g.

const Poco::Glob globPattern (pattern);
if (globPattern.match(subject))
{
    std::cout<<"Match"<<std::endl;
}
else
{
    std::cout<<"Not Matched" <<std::endl;
}

This gives me compilation time error:
passing ‘const Poco::Glob’ as ‘this’ argument of ‘bool Poco::Glob::match(const string&)’ discards qualifiers [-fpermissive]

My question is, Poco::Glob::match() does not change _pattern and _options, then why not make it a const function?
I see Poco::RegularExpression::match() being defined as const.

Thanks!