diff --git a/include/acpi/acpi_table.h b/include/acpi/acpi_table.h
index 9fba653..3a243bf 100644
--- a/include/acpi/acpi_table.h
+++ b/include/acpi/acpi_table.h
@@ -13,6 +13,7 @@
 #ifndef __ACPI_TABLE_H__
 #define __ACPI_TABLE_H__
 
+#include <dm/acpi.h>
 #include <linux/bitops.h>
 
 #define RSDP_SIG		"RSD PTR "	/* RSDP pointer signature */
@@ -48,7 +49,7 @@
 
 /* Generic ACPI header, provided by (almost) all tables */
 struct __packed acpi_table_header {
-	char signature[4];	/* ACPI signature (4 ASCII characters) */
+	char signature[ACPI_NAME_LEN];	/* ACPI signature (4 ASCII chars) */
 	u32 length;		/* Table length in bytes (incl. header) */
 	u8 revision;		/* Table version (not ACPI version!) */
 	volatile u8 checksum;	/* To make sum of entire table == 0 */
@@ -263,7 +264,7 @@
 
 /* FACS (Firmware ACPI Control Structure) */
 struct acpi_facs {
-	char signature[4];		/* "FACS" */
+	char signature[ACPI_NAME_LEN];	/* "FACS" */
 	u32 length;			/* Length in bytes (>= 64) */
 	u32 hardware_signature;		/* Hardware signature */
 	u32 firmware_waking_vector;	/* Firmware waking vector */