FYI: mpd-watchdog
is now available for Debian-based systems from my my personal APT archive, so you might as well try
wget -q -O - http://apt.kemmer.co.at/tkem.gpg | sudo apt-key add -
sudo wget -q -O /etc/apt/sources.list.d/tkem.list http://apt.kemmer.co.at/tkem.list
sudo apt-get update
sudo apt-get install mpd-watchdog
and you should be done (no reboot required).
If you have installed mpd-watchdog
as described by @JackRichardson, you have to remove the manually installed files first; sorry for the inconvenience, Jack