New versions of Unviersal Headers always define TARGET_API_MAC_CARBON either as '1' or '0'. So at some point MacPython's ubiquitous #ifndef TARGET_API_MAC_CARBON should be grep'd to: #if !TARGET_API_MAC_CARBON Though I don't think there's any particular urgancy in this, I think I was able to do it i one Replace All, or not much more.