diff --git a/MdePkg/Include/IndustryStandard/Acpi51.h b/MdePkg/Include/IndustryStandard/Acpi51.h
index 034094ea28..f38aa46a0d 100644
--- a/MdePkg/Include/IndustryStandard/Acpi51.h
+++ b/MdePkg/Include/IndustryStandard/Acpi51.h
@@ -1,8 +1,8 @@
 /** @file   
-  ACPI 5.1 definitions from the ACPI Specification Revision 5.1 July, 2014.
+  ACPI 5.1 definitions from the ACPI Specification Revision 5.1 Errata B January, 2016.
 
   Copyright (c) 2014 Hewlett-Packard Development Company, L.P.<BR>
-  Copyright (c) 2014 - 2015, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2014 - 2016, Intel Corporation. All rights reserved.<BR>
   (C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
   This program and the accompanying materials                          
   are licensed and made available under the terms and conditions of the BSD License         
@@ -537,8 +537,8 @@ typedef struct {
 ///
 /// GIC Version
 ///
-#define EFI_ACPI_5_1_GIC_V2                                   0x01
-#define EFI_ACPI_5_1_GIC_V2m                                  0x02
+#define EFI_ACPI_5_1_GIC_V1                                   0x01
+#define EFI_ACPI_5_1_GIC_V2                                   0x02
 #define EFI_ACPI_5_1_GIC_V3                                   0x03
 #define EFI_ACPI_5_1_GIC_V4                                   0x04