You have to rebuild from sources. I did this yesterday on Linux and took all the default answers from Configure except I answered y to this question:

Build a threading Perl? [n]
[download]

In summary, (as described in Perl's INSTALL file) to build perl from sources:

rm -f config.sh Policy.sh
sh Configure
make
make test
make install
[download]

For the installation directory, I normally choose something under my home directory, so I don't interfere with anyone else and so I don't need root permissions.