diff --git a/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h b/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h
index 50d4c96edb..1b26729e71 100644
--- a/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h
+++ b/MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h
@@ -56,7 +56,6 @@ typedef struct _EFI_AML_NODE_LIST EFI_AML_NODE_LIST;
 //  Size is the total size of this ACPI node buffer.
 //  Children is the children linked list of this node.
 //
-#define AML_NAME_SEG_SIZE  4
 
 struct _EFI_AML_NODE_LIST {
   UINT32                  Signature;
diff --git a/MdePkg/Include/IndustryStandard/AcpiAml.h b/MdePkg/Include/IndustryStandard/AcpiAml.h
index 74622e912e..4255ca3d70 100644
--- a/MdePkg/Include/IndustryStandard/AcpiAml.h
+++ b/MdePkg/Include/IndustryStandard/AcpiAml.h
@@ -2,7 +2,7 @@
   This file contains AML code definition in the latest ACPI spec.
 
   Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
-  Copyright (c) 2019, ARM Limited. All rights reserved.<BR>
+  Copyright (c) 2019 - 2021, Arm Limited. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -176,4 +176,9 @@
 #define AML_FIELD_CONNECTION_OP      0x02
 #define AML_FIELD_EXT_ACCESS_OP      0x03
 
+//
+// AML Name segment definitions
+//
+#define AML_NAME_SEG_SIZE            4
+
 #endif