diff --git a/InstallDetails.md b/InstallDetails.md
index 9e57e83..3b74e13 100644
--- a/InstallDetails.md
+++ b/InstallDetails.md
@@ -17,6 +17,8 @@ This isn't a complete list of dependencies though, because some of those package
 
 `zope.interface: 3.5.0, simplejson: 2.0.7, pyutil: 1.3.30, zbase32: 1.1.1, allmydata-tahoe: 1.2.0-r3353, pyOpenSSL: 0.7, Twisted: 8.1.0-r25700, Nevow: 0.9.33-r17166, foolscap: 0.3.2, zfec: 1.4.2, pycryptopp: 0.5.12, argparse: 0.8.0, setuptools: 0.6c10dev`
 
+In addition to these, if you are installing on Microsoft Windows, then you need to manually install [pywin32](http://sourceforge.net/projects/pywin32) before installing Tahoe.
+
 ## Overview
 
 Tahoe is happy to build and run in-place, from a source tree. It is not