diff --git a/include/acpi/acpi_table.h b/include/acpi/acpi_table.h
index a1bdab73059..c6a3e44a952 100644
--- a/include/acpi/acpi_table.h
+++ b/include/acpi/acpi_table.h
@@ -707,6 +707,8 @@ struct acpi_gtdt {
 	u32 virt_el2_flags;
 } __packed;
 
+#define GTDT_FLAG_INT_ACTIVE_LOW	BIT(1)
+
 /**
  * struct acpi_bgrt -  Boot Graphics Resource Table (BGRT)
  *