diff --git a/drivers/acpi/acpica/utids.c b/drivers/acpi/acpica/utids.c
index 3bb06935a2ad..3e68864ef242 100644
--- a/drivers/acpi/acpica/utids.c
+++ b/drivers/acpi/acpica/utids.c
@@ -263,8 +263,7 @@ acpi_ut_execute_CID(struct acpi_namespace_node *device_node,
 	 * 3) Size of the actual CID strings
 	 */
 	cid_list_size = sizeof(struct acpi_pnp_device_id_list) +
-	    ((count - 1) * sizeof(struct acpi_pnp_device_id)) +
-	    string_area_size;
+	    (count * sizeof(struct acpi_pnp_device_id)) + string_area_size;
 
 	cid_list = ACPI_ALLOCATE_ZEROED(cid_list_size);
 	if (!cid_list) {
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index aa236b9e6f24..735921c833f8 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -1146,7 +1146,7 @@ struct acpi_pnp_device_id {
 struct acpi_pnp_device_id_list {
 	u32 count;		/* Number of IDs in Ids array */
 	u32 list_size;		/* Size of list, including ID strings */
-	struct acpi_pnp_device_id ids[1];	/* ID array */
+	struct acpi_pnp_device_id ids[];	/* ID array */
 };
 
 /*