diff --git a/tests/test_class.py b/tests/test_class.py
index ee7467cf..73a48309 100644
--- a/tests/test_class.py
+++ b/tests/test_class.py
@@ -1,3 +1,5 @@
+from unittest import mock
+
 import pytest
 
 import env
@@ -203,6 +205,18 @@ def __init__(self):
     assert msg(exc_info.value) == expected
 
 
+@pytest.mark.parametrize(
+    "mock_return_value", [None, (1, 2, 3), m.Pet("Polly", "parrot"), m.Dog("Molly")]
+)
+def test_mock_new(mock_return_value):
+    with mock.patch.object(
+        m.Pet, "__new__", return_value=mock_return_value
+    ) as mock_new:
+        obj = m.Pet("Noname", "Nospecies")
+    assert obj is mock_return_value
+    mock_new.assert_called_once_with(m.Pet, "Noname", "Nospecies")
+
+
 def test_automatic_upcasting():
     assert type(m.return_class_1()).__name__ == "DerivedClass1"
     assert type(m.return_class_2()).__name__ == "DerivedClass2"