diff --git a/drivers/irqchip/irq-mbigen.c b/drivers/irqchip/irq-mbigen.c
index 2fa1e457190d..31d6b5a582d2 100644
--- a/drivers/irqchip/irq-mbigen.c
+++ b/drivers/irqchip/irq-mbigen.c
@@ -106,10 +106,7 @@ static inline void get_mbigen_type_reg(irq_hw_number_t hwirq,
 static inline void get_mbigen_clear_reg(irq_hw_number_t hwirq,
 					u32 *mask, u32 *addr)
 {
-	unsigned int ofst;
-
-	hwirq -= RESERVED_IRQ_PER_MBIGEN_CHIP;
-	ofst = hwirq / 32 * 4;
+	unsigned int ofst = (hwirq / 32) * 4;
 
 	*mask = 1 << (hwirq % 32);
 	*addr = ofst + REG_MBIGEN_CLEAR_OFFSET;