diff -r 37195cb81b8f Lib/test/test_email/test_message.py
--- a/Lib/test/test_email/test_message.py	Fri Sep 25 00:49:31 2015 -0400
+++ b/Lib/test/test_email/test_message.py	Fri Sep 25 16:06:38 2015 -0400
@@ -743,6 +743,31 @@
         m.set_content(content_manager=cm)
         self.assertEqual(m['MIME-Version'], '1.0')
 
+    def test_add_attachment_does_not_add_MIME_Version_in_attachment(self):
+        m = self._str_msg('')
+        cm = self._TestContentManager()
+        m.add_attachment(content_manager=cm)
+        part, = m.iter_parts()
+        self.assertNotIn('MIME-Version', part)
+
+    def test_make_mixed_adds_MIME_Version(self):
+        m = self._str_msg('')
+        self.assertNotIn('MIME-Version', m)
+        m.make_mixed()
+        self.assertEqual(m['MIME-Version'], '1.0')
+
+    def test_make_alternative_adds_MIME_Version(self):
+        m = self._str_msg('')
+        self.assertNotIn('MIME-Version', m)
+        m.make_alternative()
+        self.assertEqual(m['MIME-Version'], '1.0')
+
+    def test_make_related_adds_MIME_Version(self):
+        m = self._str_msg('')
+        self.assertNotIn('MIME-Version', m)
+        m.make_related()
+        self.assertEqual(m['MIME-Version'], '1.0')
+
     class _MIME_Version_adding_CM:
         def set_content(self, msg, *args, **kw):
             msg['MIME-Version'] = '1.0'