diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index 5ef65cf66152..3a74e4410fc0 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1057,8 +1057,8 @@ static const char *irq_remap_fault_reasons[] =
 
 const char *dmar_get_fault_reason(u8 fault_reason, int *fault_type)
 {
-	if (fault_reason >= 0x20 && (fault_reason <= 0x20 +
-				     ARRAY_SIZE(irq_remap_fault_reasons))) {
+	if (fault_reason >= 0x20 && (fault_reason - 0x20 <
+					ARRAY_SIZE(irq_remap_fault_reasons))) {
 		*fault_type = INTR_REMAP;
 		return irq_remap_fault_reasons[fault_reason - 0x20];
 	} else if (fault_reason < ARRAY_SIZE(dma_remap_fault_reasons)) {