http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56279
--- Comment #1 from Evgeny Grin <karlson2k at gmail dot com> 2013-02-10 23:04:16 UTC --- This unwanted dir is added by blindly overriding directory in gcc/config/i386/mingw32.h: #undef NATIVE_SYSTEM_HEADER_DIR #define NATIVE_SYSTEM_HEADER_DIR "/mingw/include" as result of fixing bug 52947. I think, it needs more improvement. At least for MinGW this directory should be relative to GCC files, as other include dirs. And cppdefault.c should be corrected like this: #ifdef NATIVE_SYSTEM_HEADER_DIR /* /usr/include comes dead last. */ { NATIVE_SYSTEM_HEADER_DIR, NATIVE_SYSTEM_HEADER_COMPONENT, 0, 0, NATIVE_SYSTEM_HEADER_DIR_ADD_SYSROOT, 0 }, #endif similar to GPLUSPLUS_INCLUDE_DIR part in cppdefault.c.