diff --git a/sys/arm64/arm64/mp_machdep.c b/sys/arm64/arm64/mp_machdep.c
--- a/sys/arm64/arm64/mp_machdep.c
+++ b/sys/arm64/arm64/mp_machdep.c
@@ -138,7 +138,7 @@
 
 /* Stacks for AP initialization, discarded once idle threads are started. */
 void *bootstack;
-static void *bootstacks[MAXCPU];
+static void *bootstacks[MAXCPU - 1];
 
 /* Count of started APs, used to synchronize access to bootstack. */
 static volatile int aps_started;
@@ -316,8 +316,8 @@
 	    smp_no_rendezvous_barrier, NULL);
 
 	for (cpu = 1; cpu < mp_ncpus; cpu++) {
-		if (bootstacks[cpu] != NULL)
-			kmem_free(bootstacks[cpu], MP_BOOTSTACK_SIZE);
+		if (bootstacks[cpu - 1] != NULL)
+			kmem_free(bootstacks[cpu - 1], MP_BOOTSTACK_SIZE);
 	}
 }
 SYSINIT(smp_after_idle_runnable, SI_SUB_SMP, SI_ORDER_ANY,
@@ -561,11 +561,11 @@
 	dpcpu[cpuid - 1] = (void *)(pcpup + 1);
 	dpcpu_init(dpcpu[cpuid - 1], cpuid);
 
-	bootstacks[cpuid] = kmem_malloc_domainset(DOMAINSET_PREF(domain),
+	bootstacks[cpuid - 1] = kmem_malloc_domainset(DOMAINSET_PREF(domain),
 	    MP_BOOTSTACK_SIZE, M_WAITOK | M_ZERO);
 
 	naps = atomic_load_int(&aps_started);
-	bootstack = (char *)bootstacks[cpuid] + MP_BOOTSTACK_SIZE;
+	bootstack = (char *)bootstacks[cpuid - 1] + MP_BOOTSTACK_SIZE;
 
 	printf("Starting CPU %u (%lx)\n", cpuid, target_cpu);
 	pa = pmap_extract(kernel_pmap, (vm_offset_t)mpentry);
@@ -584,9 +584,9 @@
 	if (err != 0) {
 		pcpu_destroy(pcpup);
 		dpcpu[cpuid - 1] = NULL;
-		kmem_free(bootstacks[cpuid], MP_BOOTSTACK_SIZE);
+		kmem_free(bootstacks[cpuid - 1], MP_BOOTSTACK_SIZE);
 		kmem_free(pcpup, size);
-		bootstacks[cpuid] = NULL;
+		bootstacks[cpuid - 1] = NULL;
 		mp_ncpus--;
 		return (false);
 	}