When I ran brew doctor with Homebrew, I got an error saying that a library called xz wasn’t installed.

$ brew doctor 
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry and just ignore them. Thanks!

Warning: Some installed formula are missing dependencies.
You should `brew install` the missing dependencies:

    brew install xz

Run `brew missing` for more details.

It said that brew missing would show details, so I tried it and found it was a dependency library for ImageMagick.

$ brew missing
imagemagick: xz

I’ll brew install xz.

$ brew install xz
==> Downloading https://downloads.sf.net/project/machomebrew/Bottles/xz-5.0.7.yosemite.bottle.tar.gz
######################################################################## 100.0%
==> Pouring xz-5.0.7.yosemite.bottle.tar.gz
  /usr/local/Cellar/xz/5.0.7: 58 files, 1.5M

I’ll check again with brew doctor.

$ brew doctor
Your system is ready to brew.

It’s back to normal.

That’s all from the Gemba.