diff --git a/Lib/email/feedparser.py b/Lib/email/feedparser.py
index 7c07ca86457a2aa..97d3f5144d606ff 100644
--- a/Lib/email/feedparser.py
+++ b/Lib/email/feedparser.py
@@ -320,7 +320,7 @@ def _parsegen(self):
                 self._cur.set_payload(EMPTYSTRING.join(lines))
                 return
             # Make sure a valid content type was specified per RFC 2045:6.4.
-            if (self._cur.get('content-transfer-encoding', '8bit').lower()
+            if (str(self._cur.get('content-transfer-encoding', '8bit')).lower()
                     not in ('7bit', '8bit', 'binary')):
                 defect = errors.InvalidMultipartContentTransferEncodingDefect()
                 self.policy.handle_defect(self._cur, defect)