diff --git a/falcon/media/json.py b/falcon/media/json.py
index 93b90fd7d..609b3eabd 100644
--- a/falcon/media/json.py
+++ b/falcon/media/json.py
@@ -110,7 +110,7 @@ class DatetimeEncoder(json.JSONEncoder):
             def default(self, obj):
                 if isinstance(obj, datetime):
                     return obj.isoformat()
-                super().default(obj)
+                return super().default(obj)
 
         app = falcon.App()