diff --git a/include/acpi/actbl2.h b/include/acpi/actbl2.h
index 2623f9d72e46..0d60d5df14f8 100644
--- a/include/acpi/actbl2.h
+++ b/include/acpi/actbl2.h
@@ -810,6 +810,7 @@ struct acpi_iort_smmu_v3 {
 	u8 pxm;
 	u8 reserved1;
 	u16 reserved2;
+	u32 id_mapping_index;
 };
 
 /* Values for Model field above */