diff --git a/BaseTools/Source/Python/Common/Expression.py b/BaseTools/Source/Python/Common/Expression.py
index 78c69faad6..ff9271031b 100644
--- a/BaseTools/Source/Python/Common/Expression.py
+++ b/BaseTools/Source/Python/Common/Expression.py
@@ -29,7 +29,7 @@ ERR_MATCH               = 'No matching right parenthesis.'
 ERR_STRING_TOKEN        = 'Bad string token: [%s].'
 ERR_MACRO_TOKEN         = 'Bad macro token: [%s].'
 ERR_EMPTY_TOKEN         = 'Empty token is not allowed.'
-ERR_PCD_RESOLVE         = 'PCD token cannot be resolved: [%s].'
+ERR_PCD_RESOLVE         = 'The PCD should be FeatureFlag type or FixedAtBuild type: [%s].'
 ERR_VALID_TOKEN         = 'No more valid token found from rest of string: [%s].'
 ERR_EXPR_TYPE           = 'Different types found in expression.'
 ERR_OPERATOR_UNSUPPORT  = 'Unsupported operator: [%s]'
diff --git a/BaseTools/Source/Python/Common/RangeExpression.py b/BaseTools/Source/Python/Common/RangeExpression.py
index 20581edadf..407dc06ccf 100644
--- a/BaseTools/Source/Python/Common/RangeExpression.py
+++ b/BaseTools/Source/Python/Common/RangeExpression.py
@@ -26,7 +26,7 @@ ERR_MATCH = 'No matching right parenthesis.'
 ERR_STRING_TOKEN = 'Bad string token: [%s].'
 ERR_MACRO_TOKEN = 'Bad macro token: [%s].'
 ERR_EMPTY_TOKEN = 'Empty token is not allowed.'
-ERR_PCD_RESOLVE = 'PCD token cannot be resolved: [%s].'
+ERR_PCD_RESOLVE = 'The PCD should be FeatureFlag type or FixedAtBuild type: [%s].'
 ERR_VALID_TOKEN = 'No more valid token found from rest of string: [%s].'
 ERR_EXPR_TYPE = 'Different types found in expression.'
 ERR_OPERATOR_UNSUPPORT = 'Unsupported operator: [%s]'