diff --git a/hypervisor/arch/x86/ioapic.c b/hypervisor/arch/x86/ioapic.c
index 753c2d743..4e5836588 100644
--- a/hypervisor/arch/x86/ioapic.c
+++ b/hypervisor/arch/x86/ioapic.c
@@ -362,7 +362,7 @@ void setup_ioapic_irq(void)
 			}
 
 			/* pinned irq before use it */
-			if (irq_mark_used(gsi) > NR_MAX_IRQS) {
+			if (irq_mark_used(gsi) >= NR_IRQS) {
 				pr_err("failed to alloc IRQ[%d]", gsi);
 				gsi++;
 				continue;
diff --git a/hypervisor/arch/x86/irq.c b/hypervisor/arch/x86/irq.c
index 2aa97e76b..8cbc4b3b5 100644
--- a/hypervisor/arch/x86/irq.c
+++ b/hypervisor/arch/x86/irq.c
@@ -8,7 +8,7 @@
 
 static spinlock_t exception_spinlock = { .head = 0U, .tail = 0U, };
 
-static struct irq_desc irq_desc_array[NR_MAX_IRQS];
+static struct irq_desc irq_desc_array[NR_IRQS];
 static uint32_t vector_to_irq[NR_MAX_VECTOR + 1];
 
 spurious_handler_t spurious_handler;
@@ -17,7 +17,7 @@ static void init_irq_desc(void)
 {
 	uint32_t i;
 
-	for (i = 0U; i < NR_MAX_IRQS; i++) {
+	for (i = 0U; i < NR_IRQS; i++) {
 		irq_desc_array[i].irq = i;
 		irq_desc_array[i].vector = VECTOR_INVALID;
 		spinlock_init(&irq_desc_array[i].irq_lock);
@@ -65,7 +65,7 @@ uint32_t irq_mark_used(uint32_t irq)
 
 	spinlock_rflags;
 
-	if (irq > NR_MAX_IRQS) {
+	if (irq >= NR_IRQS) {
 		return IRQ_INVALID;
 	}
 
@@ -89,7 +89,7 @@ static uint32_t alloc_irq(void)
 
 	spinlock_rflags;
 
-	for (i = irq_gsi_num(); i < NR_MAX_IRQS; i++) {
+	for (i = irq_gsi_num(); i < NR_IRQS; i++) {
 		desc = &irq_desc_array[i];
 		spinlock_irqsave_obtain(&desc->irq_lock);
 		if (desc->used == IRQ_NOT_ASSIGNED) {
@@ -99,7 +99,7 @@ static uint32_t alloc_irq(void)
 		}
 		spinlock_irqrestore_release(&desc->irq_lock);
 	}
-	return (i == NR_MAX_IRQS) ? IRQ_INVALID : i;
+	return (i == NR_IRQS) ? IRQ_INVALID : i;
 }
 
 /* need irq_lock protection before use */
@@ -133,7 +133,7 @@ static void _irq_desc_free_vector(uint32_t irq)
 	uint32_t vr;
 	uint16_t pcpu_id;
 
-	if (irq > NR_MAX_IRQS) {
+	if (irq >= NR_IRQS) {
 		return;
 	}
 
@@ -212,7 +212,7 @@ common_register_handler(uint32_t irq,
 	 * case: irq = IRQ_INVALID
 	 *	caller did not know which irq to use, and want system to
 	 *	allocate available irq for it. These irq are in range:
-	 *	nr_gsi ~ NR_MAX_IRQS
+	 *	nr_gsi ~ NR_IRQS
 	 *	a irq will be allocated and the vector will be assigned to this
 	 *	irq automatically.
 	 *
@@ -245,7 +245,7 @@ common_register_handler(uint32_t irq,
 		irq = irq_mark_used(irq);
 	}
 
-	if (irq > NR_MAX_IRQS) {
+	if (irq >= NR_IRQS) {
 		pr_err("failed to assign IRQ");
 		goto OUT;
 	}
@@ -302,7 +302,7 @@ uint32_t irq_desc_alloc_vector(uint32_t irq, bool lowpri)
 	spinlock_rflags;
 
 	/* irq should be always available at this time */
-	if (irq > NR_MAX_IRQS) {
+	if (irq >= NR_IRQS) {
 		return VECTOR_INVALID;
 	}
 
@@ -332,7 +332,7 @@ void irq_desc_try_free_vector(uint32_t irq)
 	spinlock_rflags;
 
 	/* legacy irq's vector is reserved and should not be freed */
-	if (irq > NR_MAX_IRQS || irq < NR_LEGACY_IRQ) {
+	if (irq >= NR_IRQS || irq < NR_LEGACY_IRQ) {
 		return;
 	}
 
@@ -348,7 +348,7 @@ void irq_desc_try_free_vector(uint32_t irq)
 
 uint32_t irq_to_vector(uint32_t irq)
 {
-	if (irq < NR_MAX_IRQS) {
+	if (irq < NR_IRQS) {
 		return irq_desc_array[irq].vector;
 	} else {
 		return VECTOR_INVALID;
@@ -581,7 +581,7 @@ void update_irq_handler(uint32_t irq, irq_handler_t func)
 
 	spinlock_rflags;
 
-	if (irq >= NR_MAX_IRQS) {
+	if (irq >= NR_IRQS) {
 		return;
 	}
 
@@ -703,7 +703,7 @@ void get_cpu_interrupt_info(char *str, int str_max)
 	size -= len;
 	str += len;
 
-	for (irq = 0U; irq < NR_MAX_IRQS; irq++) {
+	for (irq = 0U; irq < NR_IRQS; irq++) {
 		desc = &irq_desc_array[irq];
 		vector = irq_to_vector(irq);
 		if (desc->used != IRQ_NOT_ASSIGNED &&
diff --git a/hypervisor/arch/x86/timer.c b/hypervisor/arch/x86/timer.c
index 197fcd22b..89d1678bf 100644
--- a/hypervisor/arch/x86/timer.c
+++ b/hypervisor/arch/x86/timer.c
@@ -7,7 +7,7 @@
 #include <hypervisor.h>
 
 #define MAX_TIMER_ACTIONS	32
-#define TIMER_IRQ		(NR_MAX_IRQS - 1)
+#define TIMER_IRQ		(NR_IRQS - 1)
 #define CAL_MS			10
 #define MIN_TIMER_PERIOD_US	500
 
diff --git a/hypervisor/include/arch/x86/irq.h b/hypervisor/include/arch/x86/irq.h
index 746b97797..d1dc1368e 100644
--- a/hypervisor/include/arch/x86/irq.h
+++ b/hypervisor/include/arch/x86/irq.h
@@ -28,8 +28,8 @@
 
 #define NR_MAX_VECTOR		0xFFU
 #define VECTOR_INVALID		(NR_MAX_VECTOR + 1U)
-#define NR_MAX_IRQS		(256U + 16U)
-#define IRQ_INVALID		(NR_MAX_IRQS + 1U)
+#define NR_IRQS		(256U + 16U)
+#define IRQ_INVALID		0xffffffffU
 
 #define DEFAULT_DEST_MODE	IOAPIC_RTE_DESTLOG
 #define DEFAULT_DELIVERY_MODE	IOAPIC_RTE_DELLOPRI
diff --git a/hypervisor/include/arch/x86/per_cpu.h b/hypervisor/include/arch/x86/per_cpu.h
index 76e63faff..eaccb2d2d 100644
--- a/hypervisor/include/arch/x86/per_cpu.h
+++ b/hypervisor/include/arch/x86/per_cpu.h
@@ -20,7 +20,7 @@
 
 struct per_cpu_region {
 	uint64_t *sbuf[ACRN_SBUF_ID_MAX];
-	uint64_t irq_count[NR_MAX_IRQS];
+	uint64_t irq_count[NR_IRQS];
 	uint64_t vmexit_cnt[64];
 	uint64_t vmexit_time[64];
 	uint64_t softirq_pending;