-CHECK_INCLUDE_FILE("unistd.h" CMAKE_HAVE_UNISTD_H)
-CHECK_INCLUDE_FILE("stdlib.h" CMAKE_HAVE_STDLIB_H)
-CHECK_INCLUDE_FILE("sys/ioctl.h" CMAKE_HAVE_SYS_IOCTL_H)
-CHECK_INCLUDE_FILE("sys/socket.h" CMAKE_HAVE_SYS_SOCKET_H)
-CHECK_INCLUDE_FILE("sys/sockio.h" CMAKE_HAVE_SYS_SOCKIO_H)
-CHECK_INCLUDE_FILE("net/if.h" CMAKE_HAVE_NET_IF_H)
-CHECK_INCLUDE_FILE("netinet/in.h" CMAKE_HAVE_NETINET_IN_H)
-CHECK_INCLUDE_FILE("net/if_dl.h" CMAKE_HAVE_NET_IF_DL_H)
-CHECK_INCLUDE_FILE("net/if_arp.h" CMAKE_HAVE_NET_IF_ARP_H)
+# This is tricky as you need to figure out the proper order to
+# test the inclusion of files
+CHECK_INCLUDE_FILE_CONCAT("unistd.h" CMAKE_HAVE_UNISTD_H)
+CHECK_INCLUDE_FILE_CONCAT("stdlib.h" CMAKE_HAVE_STDLIB_H)
+CHECK_INCLUDE_FILE_CONCAT("sys/ioctl.h" CMAKE_HAVE_SYS_IOCTL_H)
+CHECK_INCLUDE_FILE_CONCAT("sys/socket.h" CMAKE_HAVE_SYS_SOCKET_H)
+CHECK_INCLUDE_FILE_CONCAT("sys/sockio.h" CMAKE_HAVE_SYS_SOCKIO_H)
+CHECK_INCLUDE_FILE_CONCAT("net/if.h" CMAKE_HAVE_NET_IF_H)
+CHECK_INCLUDE_FILE_CONCAT("netinet/in.h" CMAKE_HAVE_NETINET_IN_H)
+CHECK_INCLUDE_FILE_CONCAT("net/if_dl.h" CMAKE_HAVE_NET_IF_DL_H)
+CHECK_INCLUDE_FILE_CONCAT("net/if_arp.h" CMAKE_HAVE_NET_IF_ARP_H)