diff --git a/docs/conf.py b/docs/conf.py
index 70250439..aec987c9 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -174,7 +174,7 @@
 
 # disable cross-reference for ivar
 # patch taken from http://stackoverflow.com/a/41184353/1932023
-def patched_make_field(self, types, domain, items):
+def patched_make_field(self, types, domain, items, env=None):
     # type: (List, unicode, Tuple) -> nodes.field
     def handle_item(fieldarg, content):
         par = nodes.paragraph()