ruby: relocation error when installing tracks aur package

[jackjackk]

When I try to install tracks from aur (e.g. pacaur -S tracks), I get:

$this->bbcode_second_pass_code('', 'ruby: relocation error: /tmp/pacaurtmp-jack/tracks/src/TracksApp-tracks-4070f4e/vendor/bundle/ruby/2.3.0/gems/mysql2-0.3.16/lib/mysql2/mysql2.so: symbol mys$
l_get_client_info, version libmysqlclient_16 not defined in file libmysqlclient.so.18 with link time reference
==> ERROR: A failure occurred in build().')

I get a similar error with redmine too.
I'm running an up-to-date archlinux on a Raspberry Pi B.

Any help is highly appreciated.

Thanks,

Giacomo