diff --git a/coreapi/document.py b/coreapi/document.py
index 73b9eeb..7623cb2 100644
--- a/coreapi/document.py
+++ b/coreapi/document.py
@@ -36,7 +36,7 @@ def _key_sorting(item):
 
 # The field class, as used by Link objects:
 
-Field = namedtuple('Field', ['name', 'required', 'location', 'type', 'description', 'example'])
+Field = namedtuple('Field', ['name', 'required', 'location', 'type', 'description', 'example', 'enum'])
 Field.__new__.__defaults__ = (False, '', '', '', None)