diff -r e33b4c18af59 Lib/enum.py
--- a/Lib/enum.py	Wed Sep 16 12:18:55 2015 -0400
+++ b/Lib/enum.py	Thu Sep 17 12:31:13 2015 +0200
@@ -1,7 +1,9 @@
 import sys
-from collections import OrderedDict
 from types import MappingProxyType, DynamicClassAttribute
 
+# import delayed in __members__() property
+OrderedDict = None
+
 __all__ = ['Enum', 'IntEnum', 'unique']
 
 
@@ -113,7 +115,8 @@ class EnumMeta(type):
         # create our new Enum type
         enum_class = super().__new__(metacls, cls, bases, classdict)
         enum_class._member_names_ = []               # names in definition order
-        enum_class._member_map_ = OrderedDict()      # name->value map
+        enum_class._all_member_names_ = []           # including aliases
+        enum_class._member_map_ = {}                 # name->value map
         enum_class._member_type_ = member_type
 
         # save attributes from super classes so we know if we can take
@@ -173,6 +176,8 @@ class EnumMeta(type):
             else:
                 # Aliases don't appear in member names (only in __members__).
                 enum_class._member_names_.append(member_name)
+            # Aliases do appear in _all_member_names_
+            enum_class._all_member_names_.append(member_name)
             # performance boost for any member that would not shadow
             # a DynamicClassAttribute
             if member_name not in base_attributes:
@@ -284,6 +289,15 @@ class EnumMeta(type):
         is a read-only view of the internal mapping.
 
         """
+        global OrderedDict
+        if OrderedDict is None:
+            from collections import OrderedDict
+        if not isinstance(cls._member_map_, OrderedDict):
+            print("CONVERT", cls)
+            ordered = OrderedDict()
+            for member_name in cls._all_member_names_:
+                ordered[member_name] = cls._member_map_[member_name]
+            cls._member_map_ = ordered
         return MappingProxyType(cls._member_map_)
 
     def __repr__(cls):
@@ -557,7 +571,8 @@ def _reduce_ex_by_name(self, proto):
 def unique(enumeration):
     """Class decorator for enumerations ensuring unique member values."""
     duplicates = []
-    for name, member in enumeration.__members__.items():
+    for name in enumeration._all_member_names_:
+        member = enumeration[name]
         if name != member.name:
             duplicates.append((name, member.name))
     if duplicates:
diff -r e33b4c18af59 Lib/test/test_enum.py
--- a/Lib/test/test_enum.py	Wed Sep 16 12:18:55 2015 -0400
+++ b/Lib/test/test_enum.py	Thu Sep 17 12:31:13 2015 +0200
@@ -319,10 +319,11 @@ class TestEnum(unittest.TestCase):
         self.assertIs(Season(3), Season.AUTUMN)
         self.assertIs(Season(1), Season.SPRING)
         self.assertEqual(Season.FALL.name, 'AUTUMN')
-        self.assertEqual(
-                [k for k,v in Season.__members__.items() if v.name != k],
-                ['FALL', 'ANOTHER_SPRING'],
-                )
+	    dups = [
+		        k for k in Season._all_member_names_
+			    if Season.__members__[k].name != k
+                ]
+        self.assertEqual(dups, ['FALL', 'ANOTHER_SPRING'])
 
     def test_duplicate_name(self):
         with self.assertRaises(TypeError):