I am creating an Xcode 5.0.2 project to build libplist (https://github.com/aburgh/libplist) which includes both a C and a C++ library. The C++ code has a class String with a corresponding "String.h". Independent of that, I have a target to build the C library as a static library, and several of the C files for the C library include the system string.h. When building the C library, the files that have the directive "#include <string.h>" are actually getting the String.h file. I tried adding the option "-include /usr/include/string.h", but that didn't work. My file system is case-sensitive, but that shouldn't have any bearing in this case. Is Clang's header search case-insensitive? Could the hmap file be factor? Is there a way to force the intended behavior?