diff --git a/InstallDetails.md b/InstallDetails.md
index 5a7690e..749cef7 100644
--- a/InstallDetails.md
+++ b/InstallDetails.md
@@ -167,6 +167,10 @@ from source (as described by this page), or download pre-compiled debian
 packages for several distributions. See the DownloadDebianPackages page for
 details.
 
+=== Mac ===
+
+You will need the standard Xcode development tools installed, or at least GCC in order to build some dependencies. Note that Xcode is quite large (2.5GB) so plan accordingly if you will need to download it.
+
 === Windows ===
 
 The following procedure will install and run Tahoe on Windows.  Note that this assumes that you install Python in the default location (C:\Python26), if you choose another location you'll need to adjust the instructions below: