diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index 202cee82b74..b62a889238b 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -180,8 +180,8 @@ class TestMessageAPI(TestEmailBase):
 
     def test_byte_message_rfc822_only(self):
         # Make sure new bytes header parser also passes this.
-        with openfile('msg_46.txt', 'rb') as fp:
-            msgdata = fp.read()
+        with openfile('msg_46.txt') as fp:
+            msgdata = fp.read().encode('ascii')
         parser = email.parser.BytesHeaderParser()
         msg = parser.parsebytes(msgdata)
         out = BytesIO()
@@ -269,8 +269,8 @@ class TestMessageAPI(TestEmailBase):
 
     def test_as_bytes(self):
         msg = self._msgobj('msg_01.txt')
-        with openfile('msg_01.txt', 'rb') as fp:
-            data = fp.read()
+        with openfile('msg_01.txt') as fp:
+            data = fp.read().encode('ascii')
         self.assertEqual(data, bytes(msg))
         fullrepr = msg.as_bytes(unixfrom=True)
         lines = fullrepr.split(b'\n')
diff --git a/Misc/NEWS b/Misc/NEWS
index f6dbfdf248e..41e430fad6b 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -165,6 +165,8 @@ Library
 Tests
 -----
 
+- Issue #12037: Fix test_email for desktop Windows.
+
 - Issue #15507: test_subprocess's test_send_signal could fail if the test
   runner were run in an environment where the process inherited an ignore
   setting for SIGINT.  Restore the SIGINT handler to the desired