--- OS/os.h-FreeBSD.orig	2018-04-14 23:18:10 UTC
+++ OS/os.h-FreeBSD
@@ -12,6 +12,14 @@
 #define SIOCGIFCONF_GIVES_ADDR
 #define HAVE_SRANDOMDEV
 #define HAVE_ARC4RANDOM
+/* Applications should not call arc4random_stir() explicitly after
+   FreeBSD r227520 (approximately 1000002).
+   Set NOT_HAVE_ARC4RANDOM_STIR if the version released is past
+   that point. */
+#include <sys/param.h>
+#if __FreeBSD_version >= 1000002
+# define NOT_HAVE_ARC4RANDOM_STIR
+#endif
 
 typedef struct flock flock_t;