diff --git a/jc/utils.py b/jc/utils.py
index de2894e3..617e0355 100644
--- a/jc/utils.py
+++ b/jc/utils.py
@@ -273,6 +273,8 @@ def input_type_check(data: str) -> None:
 
 
 class timestamp:
+    __slots__ = ('string', 'format', 'naive', 'utc')
+
     def __init__(self,
                  datetime_string: str,
                  format_hint: Optional[Iterable] = None
diff --git a/tests/test_jc_utils.py b/tests/test_jc_utils.py
index 4e934b5f..61859a2b 100644
--- a/tests/test_jc_utils.py
+++ b/tests/test_jc_utils.py
@@ -73,7 +73,15 @@ class MyTests(unittest.TestCase):
         }
 
         for input_string, expected_output in datetime_map.items():
-            self.assertEqual(jc.utils.timestamp(input_string).__dict__, expected_output)
+            ts = jc.utils.timestamp(input_string)
+            ts_dict = {
+                'string': ts.string,
+                'format': ts.format,
+                'naive': ts.naive,
+                'utc': ts.utc
+            }
+
+            self.assertEqual(ts_dict, expected_output)
 
     def test_utils_convert_to_int(self):
         io_map = {