-#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
+#if defined __NetBSD__ /* NetBSD */
+/* Get __NetBSD_Version__. */
+# include <sys/param.h>
+#endif
+
+#include <errno.h> /* For detecting Plan9. */
+
+#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin */