diff --git a/HowtoContributeABuildbot.md b/HowtoContributeABuildbot.md
index 95d6f4c..da97bcd 100644
--- a/HowtoContributeABuildbot.md
+++ b/HowtoContributeABuildbot.md
@@ -2,7 +2,7 @@ Contributing a buildbot improves the quality of Tahoe-LAFS and also is integral
 
 ## Prerequisites
 
-You'll need [git](http://git-scm.com/) and [buildbot-slave](http://trac.buildbot.net/wiki/DownloadInstall) before you can proceed.
+You'll need [git](http://git-scm.com/), [Python 2.7](https://www.python.org/download/releases/2.7.8/), and setuptools before you can proceed. To install setuptools, download [ez_setup.py](https://bootstrap.pypa.io/ez_setup.py) into a directory with no Unicode characters in the path, and run it using `python ez_setup.py`. Then follow the instructions at [buildbot-slave](http://trac.buildbot.net/wiki/DownloadInstall).
 
 A buildslave makes TCP connections to the buildmaster, which `tahoe-lafs.org` operates.  You do not need a publicly routable IP address.