diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index c01fcd3d59bd9abef389516973f2caddb161ed49..600d0589fd104e56e0d80b3cae422079cfb52465 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -116,7 +116,7 @@ class GroupsSyncResult(collections.namedtuple("GroupsSyncResult", [
     __slots__ = []
 
     def __nonzero__(self):
-        return self.join or self.invite or self.leave
+        return bool(self.join or self.invite or self.leave)
 
 
 class SyncResult(collections.namedtuple("SyncResult", [