diff --git a/hypervisor/arch/x86/ioapic.c b/hypervisor/arch/x86/ioapic.c
index 7d286c611..650581f02 100644
--- a/hypervisor/arch/x86/ioapic.c
+++ b/hypervisor/arch/x86/ioapic.c
@@ -304,7 +304,7 @@ void setup_ioapic_irq(void)
 {
 	int ioapic_id;
 	uint32_t gsi;
-	int vr;
+	uint32_t vr;
 
 	spinlock_init(&ioapic_lock);
 
@@ -343,7 +343,7 @@ void setup_ioapic_irq(void)
 			 */
 			if (gsi < NR_LEGACY_IRQ) {
 				vr = irq_desc_alloc_vector(gsi, false);
-				if (vr < 0) {
+				if (vr > NR_MAX_VECTOR) {
 					pr_err("failed to alloc VR");
 					gsi++;
 					continue;
diff --git a/hypervisor/arch/x86/irq.c b/hypervisor/arch/x86/irq.c
index c38b36818..b0acfdc29 100644
--- a/hypervisor/arch/x86/irq.c
+++ b/hypervisor/arch/x86/irq.c
@@ -327,7 +327,7 @@ uint32_t irq_desc_alloc_vector(uint32_t irq, bool lowpri)
 
 	/* irq should be always available at this time */
 	if (irq > NR_MAX_IRQS)
-		return false;
+		return VECTOR_INVALID;
 
 	desc = irq_desc_base + irq;
 	spinlock_irqsave_obtain(&desc->irq_lock);