diff --git a/BaseTools/Source/Python/Ecc/Check.py b/BaseTools/Source/Python/Ecc/Check.py
index 6087abfa4d..7a012617fd 100644
--- a/BaseTools/Source/Python/Ecc/Check.py
+++ b/BaseTools/Source/Python/Ecc/Check.py
@@ -1,6 +1,7 @@
 ## @file
 # This file is used to define checkpoints used by ECC tool
 #
+# Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
 # Copyright (c) 2008 - 2020, Intel Corporation. All rights reserved.<BR>
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -1438,7 +1439,7 @@ class Check(object):
             RecordSet = EccGlobalData.gDb.TblFile.Exec(SqlCommand)
             for Record in RecordSet:
                 Name = Record[1].replace('#ifndef', '').strip()
-                if Name[-1] != '_':
+                if Name[0] == '_' or Name[-1] != '_' or Name[-2] == '_':
                     if not EccGlobalData.gException.IsException(ERROR_NAMING_CONVENTION_CHECK_IFNDEF_STATEMENT, Name):
                         EccGlobalData.gDb.TblReport.Insert(ERROR_NAMING_CONVENTION_CHECK_IFNDEF_STATEMENT, OtherMsg="The #ifndef name [%s] does not follow the rules" % (Name), BelongsToTable=FileTable, BelongsToItem=Record[0])
 
diff --git a/BaseTools/Source/Python/Ecc/EccToolError.py b/BaseTools/Source/Python/Ecc/EccToolError.py
index 0ff3b42674..d97bf7948c 100644
--- a/BaseTools/Source/Python/Ecc/EccToolError.py
+++ b/BaseTools/Source/Python/Ecc/EccToolError.py
@@ -1,6 +1,7 @@
 ## @file
 # Standardized Error Handling infrastructures.
 #
+# Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
 # Copyright (c) 2008 - 2018, Intel Corporation. All rights reserved.<BR>
 # SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -161,7 +162,7 @@ gEccErrorMessage = {
     ERROR_NAMING_CONVENTION_CHECK_ALL : "",
     ERROR_NAMING_CONVENTION_CHECK_DEFINE_STATEMENT : "Only capital letters are allowed to be used for #define declarations",
     ERROR_NAMING_CONVENTION_CHECK_TYPEDEF_STATEMENT : "Only capital letters are allowed to be used for typedef declarations",
-    ERROR_NAMING_CONVENTION_CHECK_IFNDEF_STATEMENT : "The #ifndef at the start of an include file should use both prefix and postfix underscore characters, '_'",
+    ERROR_NAMING_CONVENTION_CHECK_IFNDEF_STATEMENT : "The #ifndef at the start of an include file should have one postfix underscore, and no prefix underscore character '_'",
     ERROR_NAMING_CONVENTION_CHECK_PATH_NAME : """Path name does not follow the rules: 1. First character should be upper case 2. Must contain lower case characters 3. No white space characters""",
     ERROR_NAMING_CONVENTION_CHECK_VARIABLE_NAME : """Variable name does not follow the rules: 1. First character should be upper case 2. Must contain lower case characters 3. No white space characters 4. Global variable name must start with a 'g'""",
     ERROR_NAMING_CONVENTION_CHECK_FUNCTION_NAME : """Function name does not follow the rules: 1. First character should be upper case 2. Must contain lower case characters 3. No white space characters""",