diff --git a/usr.sbin/ypbind/ypbind.c b/usr.sbin/ypbind/ypbind.c
index 0083cf8667c..700365f5575 100644
--- a/usr.sbin/ypbind/ypbind.c
+++ b/usr.sbin/ypbind/ypbind.c
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
 #include <sys/signal.h>
 #include <sys/socket.h>
 #include <sys/file.h>
@@ -465,6 +466,9 @@ main(int argc, char *argv[])
 
 	openlog(argv[0], LOG_PID, LOG_DAEMON);
 
+	if (madvise(NULL, 0, MADV_PROTECT) != 0)
+		syslog(LOG_WARNING, "madvise(): %m");
+
 	/* Kick off the default domain */
 	broadcast(ypbindlist);