diff --git a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
index d987bbf441..8d8a3e2789 100644
--- a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
+++ b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
@@ -21,11 +21,15 @@ from Common.BuildToolError import RESOURCE_NOT_AVAILABLE
 from Common.BuildToolError import OPTION_MISSING
 from Common.BuildToolError import BUILD_ERROR
 
-class OrderedListDict(OrderedDict, defaultdict):
+class OrderedListDict(OrderedDict):
     def __init__(self, *args, **kwargs):
         super(OrderedListDict, self).__init__(*args, **kwargs)
         self.default_factory = list
 
+    def __missing__(self, key):
+        self[key] = Value = self.default_factory()
+        return Value
+
 ## Get all packages from platform for specified arch, target and toolchain
 #
 #  @param Platform: DscBuildData instance