diff --git a/src/projex/rest.py b/src/projex/rest.py
index <HASH>..<HASH> 100644
--- a/src/projex/rest.py
+++ b/src/projex/rest.py
@@ -116,6 +116,8 @@ def py2json(py_obj):
         return py_obj.strftime('%Y-%m-%d')

     elif type(py_obj) == datetime.time:

         return py_obj.strftime('%H:%M:%S:%f')

+    elif type(py_obj) == set:

+        return list(py_obj)

     else:

         # look through custom plugins

         for encoder in _encoders:
* json cannot serialize set's, converting to a list