diff -r 5388fa98f7a3 Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Tue Sep 15 23:59:00 2015 +0200
+++ b/Lib/unittest/mock.py	Wed Sep 16 22:59:56 2015 -0700
@@ -1557,8 +1557,12 @@
             in_dict = _importer(in_dict)
         self.in_dict = in_dict
         # support any argument supported by dict(...) constructor
-        self.values = dict(values)
-        self.values.update(kwargs)
+        # values is a mapping
+        if hasattr(values, "items") and callable(values.items):
+            self.values = list(values.items())
+        else: # values is an iterable 
+            self.values = list(values)
+        self.values.extend(kwargs.items())
         self.clear = clear
         self._original = None
 
@@ -1615,8 +1619,8 @@
             in_dict.update(values)
         except AttributeError:
             # dict like object with no update method
-            for key in values:
-                in_dict[key] = values[key]
+            for key, value in values:
+                in_dict[key] = value
 
 
     def _unpatch_dict(self):
diff -r 5388fa98f7a3 Lib/unittest/test/testmock/testpatch.py
--- a/Lib/unittest/test/testmock/testpatch.py	Tue Sep 15 23:59:00 2015 +0200
+++ b/Lib/unittest/test/testmock/testpatch.py	Wed Sep 16 22:59:56 2015 -0700
@@ -4,6 +4,7 @@
 
 import os
 import sys
+from collections import OrderedDict
 
 import unittest
 from unittest.test.testmock import support
@@ -625,6 +626,30 @@
 
         self.assertEqual(foo.values, original)
 
+    def test_patch_dict_with_orderddict(self):
+        foo = OrderedDict()
+        foo['a'] = object()
+        foo['b'] = 'something'
+
+        original = foo.copy()
+
+        update_values = zip('cdefghijklmnopqrstuvwxyz', range(26))
+
+        @patch.dict(foo, OrderedDict(update_values))
+        def test():
+            self.assertEqual(list(foo), sorted(foo))
+
+        test()
+
+        self.assertEqual(foo, original)
+
+        @patch.dict(foo, update_values) 
+        def test():
+            self.assertEqual(list(foo), sorted(foo))
+
+        test()
+
+        self.assertEqual(foo, original)
 
     def test_name_preserved(self):
         foo = {}