build error--missing header

While compiling MoreFilesX.o, I get this error:

In file included from
/Users/evan/src/firefox/mozilla/xpcom/MoreFiles/MoreFilesX.c:73:
/System/Library/Frameworks/Carbon.framework/Headers/Carbon.h:33:37:
CarbonSound/CarbonSound.h: No such file or directory
/Users/evan/src/firefox/mozilla/xpcom/MoreFiles/MoreFilesX.c: In
function `GetTempBuffer':
/Users/evan/src/firefox/mozilla/xpcom/MoreFiles/MoreFilesX.c:2654:
warning: comparison between signed and unsigned
make[4]: *** [MoreFilesX.o] Error 1
make[3]: *** [libs] Error 2
make[2]: *** [tier_2] Error 2
make[1]: *** [default] Error 2
make: *** [build] Error 2

It looks like I have a CarbonSound.h hanging out in
/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/CarbonSound.framework/Versions/A/Headers/CarbonSound.h

I installed everything described http://www.mozilla.org/build/mac.html
and used the standard build options. Any idea why it wouldn't be able
to find the file?