Hi. When you build gcc from sources, a few headers are installed to /usr/lib/gcc/x86_64-redhat-linux/6.1.1/include-fixed/ The exact list of these headers depends on packages installed. For example: xorg-x11-proto-devel: X11/Xw32defs.h unix => __unix__ openssl-devel: openssl/bn.h linux => __linux__ libpaper-devel: paper.h __STDC__ => __STRICT_ANSI__ If you install a newer package version, the headers in "/usr/include/" get replaced and the headers in "include-fixed/" become outdated. How is this supposed to work?