diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 29047880f..edf68287a 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -2939,7 +2939,6 @@ class TestType(unittest.TestCase):
             A.__qualname__ = b'B'
         self.assertEqual(A.__qualname__, 'D.E')
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: '__firstlineno__' unexpectedly found in mappingproxy({'__firstlineno__': 42, '__module__': 'testmodule', '__dict__': <attribute '__dict__' of 'A' objects>, '__doc__': None})
     def test_type_firstlineno(self):
         A = type('A', (), {'__firstlineno__': 42})
         self.assertEqual(A.__name__, 'A')
diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
index 2eb7e8b4a..456d94534 100644
--- a/Lib/test/test_inspect/test_inspect.py
+++ b/Lib/test/test_inspect/test_inspect.py
@@ -910,7 +910,6 @@ class TestGetsourceStdlib(unittest.TestCase):
         self.assertRaises(OSError, inspect.getsource, tomllib.TOMLDecodeError)
         self.assertRaises(OSError, inspect.getsourcelines, tomllib.TOMLDecodeError)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: OSError not raised by getsource
     def test_getsource_stdlib_abc(self):
         # Pure Python implementation
         abc = import_helper.import_fresh_module('abc', blocked=['_abc'])
diff --git a/crates/vm/src/builtins/type.rs b/crates/vm/src/builtins/type.rs
index 3a1cebb9d..5970c30fb 100644
--- a/crates/vm/src/builtins/type.rs
+++ b/crates/vm/src/builtins/type.rs
@@ -1648,9 +1648,9 @@ impl PyType {
     #[pygetset(setter)]
     fn set___module__(&self, value: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
         self.check_set_special_type_attr(identifier!(vm, __module__), vm)?;
-        self.attributes
-            .write()
-            .insert(identifier!(vm, __module__), value);
+        let mut attributes = self.attributes.write();
+        attributes.swap_remove(identifier!(vm, __firstlineno__));
+        attributes.insert(identifier!(vm, __module__), value);
         Ok(())
     }
 
diff --git a/crates/vm/src/vm/context.rs b/crates/vm/src/vm/context.rs
index 1edb8656e..dc0af9386 100644
--- a/crates/vm/src/vm/context.rs
+++ b/crates/vm/src/vm/context.rs
@@ -135,6 +135,7 @@ declare_const_name! {
     __eq__,
     __exit__,
     __file__,
+    __firstlineno__,
     __float__,
     __floor__,
     __floordiv__,