diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index dfd7876..fe6d4be 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -816,7 +816,7 @@
 
 static unsigned long hpet_calibrate(struct hpets *hpetp)
 {
-	unsigned long ret = -1;
+	unsigned long ret = ~0UL;
 	unsigned long tmp;
 
 	/*
@@ -1001,6 +1001,9 @@
 		irqp = &res->data.extended_irq;
 
 		for (i = 0; i < irqp->interrupt_count; i++) {
+			if (hdp->hd_nirqs >= HPET_MAX_TIMERS)
+				break;
+
 			irq = acpi_register_gsi(NULL, irqp->interrupts[i],
 				      irqp->triggering, irqp->polarity);
 			if (irq < 0)