diff --git a/usr.sbin/ndp/ndp.c b/usr.sbin/ndp/ndp.c
index 9d9ae02dc1e..dcb3b5e3571 100644
--- a/usr.sbin/ndp/ndp.c
+++ b/usr.sbin/ndp/ndp.c
@@ -1171,7 +1171,7 @@ rtrlist(void)
 	size_t l;
 	struct timeval now;
 
-	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), NULL, &l, NULL, 0) < 0) {
+	if (sysctl(mib, nitems(mib), NULL, &l, NULL, 0) < 0) {
 		xo_err(1, "sysctl(ICMPV6CTL_ND6_DRLIST)");
 		/*NOTREACHED*/
 	}
@@ -1182,7 +1182,7 @@ rtrlist(void)
 		xo_err(1, "malloc");
 		/*NOTREACHED*/
 	}
-	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), buf, &l, NULL, 0) < 0) {
+	if (sysctl(mib, nitems(mib), buf, &l, NULL, 0) < 0) {
 		xo_err(1, "sysctl(ICMPV6CTL_ND6_DRLIST)");
 		/*NOTREACHED*/
 	}
@@ -1257,7 +1257,7 @@ plist(void)
 	int ninflags = opts.nflag ? NI_NUMERICHOST : 0;
 	char namebuf[NI_MAXHOST];
 
-	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), NULL, &l, NULL, 0) < 0) {
+	if (sysctl(mib, nitems(mib), NULL, &l, NULL, 0) < 0) {
 		xo_err(1, "sysctl(ICMPV6CTL_ND6_PRLIST)");
 		/*NOTREACHED*/
 	}
@@ -1266,7 +1266,7 @@ plist(void)
 		xo_err(1, "malloc");
 		/*NOTREACHED*/
 	}
-	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), buf, &l, NULL, 0) < 0) {
+	if (sysctl(mib, nitems(mib), buf, &l, NULL, 0) < 0) {
 		xo_err(1, "sysctl(ICMPV6CTL_ND6_PRLIST)");
 		/*NOTREACHED*/
 	}