diff --git a/mypyc/test-data/fixtures/ir.py b/mypyc/test-data/fixtures/ir.py
index c041c661741c..ecca7346f036 100644
--- a/mypyc/test-data/fixtures/ir.py
+++ b/mypyc/test-data/fixtures/ir.py
@@ -47,6 +47,7 @@ def __ne__(self, x: object) -> bool: pass
 class type:
     def __init__(self, o: object) -> None: ...
     def __or__(self, o: object) -> Any: ...
+    def __new__(cls, *args: object) -> Any: ...
     __name__ : str
     __annotations__: Dict[str, Any]
 
diff --git a/mypyc/test-data/run-classes.test b/mypyc/test-data/run-classes.test
index 6f1217bd36e6..1f2466179e6d 100644
--- a/mypyc/test-data/run-classes.test
+++ b/mypyc/test-data/run-classes.test
@@ -811,7 +811,7 @@ def test_classmethod_with_allow_interpreted() -> None:
 
 [file interp.py]
 def make_interpreted_subclass(base):
-    class Sub(base):
+    class Sub(base):  # type: ignore[misc, valid-type]
         @classmethod
         def g(cls, x: int) -> int:
             return x + 3
@@ -2473,7 +2473,7 @@ def test_interpreted_subclass() -> None:
 from testutil import assertRaises
 
 def define_interpreted_subclass(b):
-    class DerivedInterpreted1(b):
+    class DerivedInterpreted1(b):  # type: ignore[misc, valid-type]
         def __init__(self):
             # Don't call base class __init__
             pass
@@ -2486,10 +2486,10 @@ def define_interpreted_subclass(b):
     with assertRaises(AttributeError):
         del d1.x
 
-    class DerivedInterpreted1(b):
+    class DerivedInterpreted2(b):  # type: ignore[misc, valid-type]
         def __init__(self):
             super().__init__('y')
-    d2 = DerivedInterpreted1()
+    d2 = DerivedInterpreted2()
     assert d2.x == 5
     assert d2.s == 'y'
     with assertRaises(AttributeError):
diff --git a/mypyc/test/test_run.py b/mypyc/test/test_run.py
index 172a1016dd91..b55847785e25 100644
--- a/mypyc/test/test_run.py
+++ b/mypyc/test/test_run.py
@@ -204,6 +204,7 @@ def run_case_step(self, testcase: DataDrivenTestCase, incremental_step: int) ->
         options.preserve_asts = True
         options.allow_empty_bodies = True
         options.incremental = self.separate
+        options.check_untyped_defs = True
 
         # Avoid checking modules/packages named 'unchecked', to provide a way
         # to test interacting with code we don't have types for.