diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
index 84c5f0468d..3f12a33050 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI parser
 
-  Copyright (c) 2016 - 2019, ARM Limited. All rights reserved.
+  Copyright (c) 2016 - 2020, ARM Limited. All rights reserved.
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
@@ -673,7 +673,7 @@ DumpGas (
   IN UINT8*        Ptr
   )
 {
-  DumpGasStruct (Ptr, 2, GAS_LENGTH);
+  DumpGasStruct (Ptr, 2, sizeof (EFI_ACPI_6_3_GENERIC_ADDRESS_STRUCTURE));
 }
 
 /**
@@ -694,7 +694,7 @@ DumpAcpiHeader (
            0,
            "ACPI Table Header",
            Ptr,
-           ACPI_DESCRIPTION_HEADER_LENGTH,
+           sizeof (EFI_ACPI_DESCRIPTION_HEADER),
            PARSER_PARAMS (AcpiHeaderParser)
            );
 }
@@ -728,7 +728,7 @@ ParseAcpiHeader (
                   0,
                   NULL,
                   Ptr,
-                  ACPI_DESCRIPTION_HEADER_LENGTH,
+                  sizeof (EFI_ACPI_DESCRIPTION_HEADER),
                   PARSER_PARAMS (AcpiHeaderParser)
                   );
 
diff --git a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
index 6deee3542e..f81ccac7e1 100644
--- a/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
+++ b/ShellPkg/Library/UefiShellAcpiViewCommandLib/AcpiParser.h
@@ -1,7 +1,7 @@
 /** @file
   Header file for ACPI parser
 
-  Copyright (c) 2016 - 2019, ARM Limited. All rights reserved.
+  Copyright (c) 2016 - 2020, ARM Limited. All rights reserved.
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
@@ -396,26 +396,6 @@ ParseAcpi (
   { L"Creator Revision", 4, 32, L"0x%X", NULL,    \
     (VOID**)&(Info)->CreatorRevision, NULL, NULL }
 
-/**
-  Length of the ACPI GAS structure.
-
-  NOTE: This might normally be defined as
-        sizeof (EFI_ACPI_6_2_GENERIC_ADDRESS_STRUCTURE).
-        However, we deliberately minimise any reference to the EDK2 ACPI
-        headers in an attempt to provide cross checking.
-**/
-#define GAS_LENGTH                     12
-
-/**
-  Length of the ACPI Header structure.
-
-  NOTE: This might normally be defined as
-        sizeof (EFI_ACPI_DESCRIPTION_HEADER).
-        However, we deliberately minimise any reference to the EDK2 ACPI
-        headers in an attempt to provide cross checking.
-**/
-#define ACPI_DESCRIPTION_HEADER_LENGTH  36
-
 /**
   This function indents and traces the GAS structure as described by the GasParser.