Index: head/sys/kern/stack_protector.c
===================================================================
--- head/sys/kern/stack_protector.c	(revision 284461)
+++ head/sys/kern/stack_protector.c	(revision 284462)
@@ -1,31 +1,30 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/systm.h>
 #include <sys/libkern.h>
 
 long __stack_chk_guard[8] = {};
 void __stack_chk_fail(void);
 
 void
 __stack_chk_fail(void)
 {
 
 	panic("stack overflow detected; backtrace may be corrupted");
 }
 
-#define __arraycount(__x)	(sizeof(__x) / sizeof(__x[0]))
 static void
 __stack_chk_init(void *dummy __unused)
 {
 	size_t i;
-	long guard[__arraycount(__stack_chk_guard)];
+	long guard[nitems(__stack_chk_guard)];
 
 	arc4rand(guard, sizeof(guard), 0);
-	for (i = 0; i < __arraycount(guard); i++)
+	for (i = 0; i < nitems(guard); i++)
 		__stack_chk_guard[i] = guard[i];
 }
 SYSINIT(stack_chk, SI_SUB_RANDOM, SI_ORDER_ANY, __stack_chk_init, NULL);