diff --git a/custom_components/grocy/json_encode.py b/custom_components/grocy/json_encode.py
index a4482a9..a4d49c2 100644
--- a/custom_components/grocy/json_encode.py
+++ b/custom_components/grocy/json_encode.py
@@ -1,5 +1,6 @@
 import json
 from datetime import datetime
+from datetime import date
 from pathlib import Path
 from typing import Any
 
@@ -17,6 +18,8 @@ def default(self, o: Any) -> Any:
             return o.barcode
         if isinstance(o, datetime):
             return o.isoformat()
+        if isinstance(o, date):
+            return o.isoformat()
         if isinstance(o, set):
             return list(o)
         if isinstance(o, Path):