diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 0d4ddf8e553e..8054bf818a11 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -163,9 +163,9 @@ void
 cpu_add(u_int apic_id, char boot_cpu)
 {
 
-	if (apic_id > MAXCPU) {
+	if (apic_id >= MAXCPU) {
 		printf("SMP: CPU %d exceeds maximum CPU %d, ignoring\n",
-		    apic_id, MAXCPU);
+		    apic_id, MAXCPU - 1);
 		return;
 	}
 	KASSERT(cpu_info[apic_id].cpu_present == 0, ("CPU %d added twice",
diff --git a/sys/amd64/amd64/mptable.c b/sys/amd64/amd64/mptable.c
index f0a988347c56..a65ca0f58395 100644
--- a/sys/amd64/amd64/mptable.c
+++ b/sys/amd64/amd64/mptable.c
@@ -54,7 +54,7 @@ __FBSDID("$FreeBSD$");
 /* string defined by the Intel MP Spec as identifying the MP table */
 #define	MP_SIG			0x5f504d5f	/* _MP_ */
 
-#define	NAPICID			32	/* Max number of I/O APIC's */
+#define	NAPICID			32	/* Max number of APIC's */
 
 #define BIOS_BASE		(0xf0000)
 #define BIOS_SIZE		(0x10000)
@@ -811,7 +811,7 @@ mptable_hyperthread_fixup(u_int id_mask)
 	 * physical processor.  If any of those ID's are
 	 * already in the table, then kill the fixup.
 	 */
-	for (id = 0; id <= MAXCPU; id++) {
+	for (id = 0; id < NAPICID; id++) {
 		if ((id_mask & 1 << id) == 0)
 			continue;
 		/* First, make sure we are on a logical_cpus boundary. */