RMagick on Debian Testing

I had trouble installing RMagick on a Debian Testing box today. I have Image Magick and related libraries installed - but this was the error:

configure: error: Can't install RMagick. Can't find Magick-config or GraphicsMagick-config program.
RMagick configuration failed with status 1.

After much searching, this was what I needed.

sudo apt-get install libmagick9-dev

You will of course need ruby1.8-dev as well, but if you are doing any other Ruby on Rails work with Debian, you probably already have it.