diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index 2decadb00..ae7901551 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -30,6 +30,9 @@ class ThirdPartyProtocolsServlet(RestServlet):
 
     META = {
         # TODO(paul): Declare kinds of metadata in here
+        "gitter": {
+            "user_fields": ["username"],
+        }
     }
 
     def __init__(self, hs):