diff --git a/CompileError.md b/CompileError.md
index 877f8fa..077bacc 100644
--- a/CompileError.md
+++ b/CompileError.md
@@ -4,18 +4,28 @@ See also [Installation](Installation) for pre-built packages for your operating
 
 Sometimes running `python setup.py build` results in an error message about a compile failure. This page will tell you how to get past that problem.
 
-A typical error message when building is:
+A typical error message when building on Windows is:
 
 ```
 distutils.errors.DistutilsError: Setup script exited with error: Unable to find vcvarsall.bat
 ```
 
-That's on Windows. On Linux a typical error message is:
+On Linux a typical error message is:
 
 ```
 error: Python.h: No such file or directory
 ```
 
+On Mac OS X a typical error message is:
+
+```
+unable to execute clang: No such file or directory
+```
+
+### in brief
+
+The short version, for people who don't want to read this whole page is: write to the tahoe-dev mailing list and ask if some volunteer will kindly build a binary package of the necessary library for your operating system and your version of Python. In your request, include: 1. the entire output from your attempt to build (which will include an error message like one of those above), 2. what operating system you are using, 3. what version of Python you are using (`python -V`), 4. some nice words like "please" and "thank you".
+
 ### Why This Happens
 
 First of all, the Tahoe-LAFS software itself is written in 100% pure Python and never gets compiled. However, Tahoe-LAFS uses several libraries which themselves contain native C or C++ code that needs to be compiled. Currently there are six such libraries that Tahoe-LAFS uses: `Twisted`, `pyOpenSSL`, `pycrypto`, `pycryptopp`, `zfec`, and `zope.interface`.