1 files changed, 4 insertions, 2 deletions
diff --git a/BaseTools/Source/Python/AutoGen/GenMake.py b/BaseTools/Source/Python/AutoGen/GenMake.py
index 4f85a93055..3185ebe368 100755
--- a/BaseTools/Source/Python/AutoGen/GenMake.py
+++ b/BaseTools/Source/Python/AutoGen/GenMake.py
@@ -205,10 +205,12 @@ class BuildFile(object):
     def GetRemoveDirectoryCommand(self, DirList):
         return [self._RD_TEMPLATE_[self._FileType] % {'dir':Dir} for Dir in DirList]
 
-    def PlaceMacro(self, Path, MacroDefinitions={}):
+    def PlaceMacro(self, Path, MacroDefinitions=None):
         if Path.startswith("$("):
             return Path
         else:
+            if MacroDefinitions is None:
+                MacroDefinitions = {}
             PathLength = len(Path)
             for MacroName in MacroDefinitions:
                 MacroValue = MacroDefinitions[MacroName]
@@ -1762,4 +1764,4 @@ def GetDependencyList(AutoGenObject, FileCache, File, ForceList, SearchPathList)
 
 # This acts like the main() function for the script, unless it is 'import'ed into another script.
 if __name__ == '__main__':
-    pass
-\ No newline at end of file
+    pass