-AC_CHECK_LIB([rt], [main],, AC_MSG_ERROR("required library 'rt' is missing"))
+case "${host}" in
+ *-*-linux*)
+ AC_CHECK_LIB([rt], [main],, AC_MSG_ERROR("required library 'rt' is missing"))
+ AC_CHECK_LIB([udev], [main],, AC_MSG_ERROR("required library 'udev' is missing"))
+ REQUIRES="udev"
+ ;;
+ *-apple-darwin*)
+ LIBS+="-framework CoreVideo -framework IOKit"
+ ;;
+esac
+