1 files changed, 7 insertions, 3 deletions
diff --git a/BaseTools/Source/Python/Common/StringUtils.py b/BaseTools/Source/Python/Common/StringUtils.py
index 0febbc0034..73dafa797a 100644
--- a/BaseTools/Source/Python/Common/StringUtils.py
+++ b/BaseTools/Source/Python/Common/StringUtils.py
@@ -243,8 +243,10 @@ def SplitModuleType(Key):
 #
 # @retval NewList           A new string list whose macros are replaced
 #
-def ReplaceMacros(StringList, MacroDefinitions={}, SelfReplacement=False):
+def ReplaceMacros(StringList, MacroDefinitions=None, SelfReplacement=False):
     NewList = []
+    if MacroDefinitions is None:
+        MacroDefinitions = {}
     for String in StringList:
         if isinstance(String, type('')):
             NewList.append(ReplaceMacro(String, MacroDefinitions, SelfReplacement))
@@ -264,8 +266,10 @@ def ReplaceMacros(StringList, MacroDefinitions={}, SelfReplacement=False):
 #
 # @retval string            The string whose macros are replaced
 #
-def ReplaceMacro(String, MacroDefinitions={}, SelfReplacement=False, RaiseError=False):
+def ReplaceMacro(String, MacroDefinitions=None, SelfReplacement=False, RaiseError=False):
     LastString = String
+    if MacroDefinitions is None:
+        MacroDefinitions = {}
     while String and MacroDefinitions:
         MacroUsed = GlobalData.gMacroRefPattern.findall(String)
         # no macro found in String, stop replacing
@@ -298,7 +302,7 @@ def ReplaceMacro(String, MacroDefinitions={}, SelfReplacement=False, RaiseError=
 #
 # @retval Path Formatted path
 #
-def NormPath(Path, Defines={}):
+def NormPath(Path, Defines=None):
     IsRelativePath = False
     if Path:
         if Path[0] == '.':