diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0795665e5..add473fbe 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,3 +1,14 @@
+v4.10.1
+-------
+
+* Fix Validator.evolve (and APIs like ``iter_errors`` which call it) for cases
+  where the validator class has been subclassed. Doing so wasn't intended to be
+  public API, but given it didn't warn or raise an error it's of course
+  understandable. The next release however will make it warn (and a future one
+  will make it error). If you need help migrating usage of inheriting from a
+  validator class feel free to open a discussion and I'll try to give some
+  guidance (#982).
+
 v4.10.0
 -------
 
diff --git a/jsonschema/tests/test_validators.py b/jsonschema/tests/test_validators.py
index 064336216..87fa1edeb 100644
--- a/jsonschema/tests/test_validators.py
+++ b/jsonschema/tests/test_validators.py
@@ -1463,6 +1463,38 @@ def test_it_delegates_to_a_ref_resolver(self):
         with self.assertRaises(exceptions.ValidationError):
             validator.validate(None)
 
+    def test_evolve(self):
+        ref, schema = "someCoolRef", {"type": "integer"}
+        resolver = validators.RefResolver("", {}, store={ref: schema})
+
+        validator = self.Validator(schema, resolver=resolver)
+        new = validator.evolve(schema={"type": "string"})
+
+        expected = self.Validator({"type": "string"}, resolver=resolver)
+
+        self.assertEqual(new, expected)
+        self.assertNotEqual(new, validator)
+
+    def test_evolve_with_subclass(self):
+        """
+        Subclassing validators isn't supported public API, but some users have
+        done it, because we don't actually error entirely when it's done :/
+
+        We need to deprecate doing so first to help as many of these users
+        ensure they can move to supported APIs, but this test ensures that in
+        the interim, we haven't broken those users.
+        """
+
+        @attr.s
+        class OhNo(self.Validator):
+            foo = attr.ib(factory=lambda: [1, 2, 3])
+
+        validator = OhNo({})
+        self.assertEqual(validator.foo, [1, 2, 3])
+
+        new = validator.evolve(schema={"type": "integer"})
+        self.assertEqual(new.foo, [1, 2, 3])
+
     def test_it_delegates_to_a_legacy_ref_resolver(self):
         """
         Legacy RefResolvers support only the context manager form of
diff --git a/jsonschema/validators.py b/jsonschema/validators.py
index 4d6ced011..c799d4075 100644
--- a/jsonschema/validators.py
+++ b/jsonschema/validators.py
@@ -203,7 +203,7 @@ def check_schema(cls, schema):
 
         def evolve(self, **changes):
             schema = changes.setdefault("schema", self.schema)
-            NewValidator = validator_for(schema, default=Validator)
+            NewValidator = validator_for(schema, default=self.__class__)
 
             # Essentially reproduces attr.evolve, but may involve instantiating
             # a different class than this one.