diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index f7110f3b4092..bf5d28b6e30e 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -510,7 +510,7 @@ def on_GET(self, request):
         # if the lookup is allowed so we don't need to do it here.
         ret = yield self.identity_handler.lookup_3pid(id_server, medium, address)
 
-        respond_with_json(200, ret)
+        defer.returnValue((200, ret))
 
 
 class ThreepidBulkLookupRestServlet(RestServlet):
@@ -537,7 +537,7 @@ def on_POST(self, request):
             body["id_server"], body["threepids"],
         )
 
-        respond_with_json(200, ret)
+        defer.returnValue((200, ret))
 
 
 class WhoamiRestServlet(RestServlet):