diff --git a/atst/utils/json.py b/atst/utils/json.py
index a489fcaa..4ce7bd8d 100644
--- a/atst/utils/json.py
+++ b/atst/utils/json.py
@@ -1,4 +1,5 @@
 from flask.json import JSONEncoder
+from datetime import date
 from atst.models.attachment import Attachment
 
 
@@ -6,4 +7,6 @@ class CustomJSONEncoder(JSONEncoder):
     def default(self, obj):
         if isinstance(obj, Attachment):
             return obj.filename
+        if isinstance(obj, date):
+            return obj.strftime("%Y-%m-%d")
         return JSONEncoder.default(self, obj)