diff --git a/Lib/email/Message.py b/Lib/email/Message.py
index 0f513f5..6dfa84b 100644
--- a/Lib/email/Message.py
+++ b/Lib/email/Message.py
@@ -186,7 +186,7 @@
         if i is None:
             payload = self._payload
         elif not isinstance(self._payload, ListType):
-            raise TypeError, i
+            raise TypeError, 'Expected list, got %s' % type(self._payload)
         else:
             payload = self._payload[i]
         if decode: