diff --git a/Lib/test/test_sqlite3/test_regression.py b/Lib/test/test_sqlite3/test_regression.py
index 2f59cf9ba..5560365fd 100644
--- a/Lib/test/test_sqlite3/test_regression.py
+++ b/Lib/test/test_sqlite3/test_regression.py
@@ -305,7 +305,6 @@ class RegressionTests(MemoryDatabaseMixin, unittest.TestCase):
                 datetime.datetime(2012, 4, 4, 15, 6, 0, 123456),
             ])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; error message mismatch
     def test_invalid_isolation_level_type(self):
         # isolation level is a string, not an integer
         regex = "isolation_level must be str or None"
diff --git a/crates/stdlib/src/_sqlite3.rs b/crates/stdlib/src/_sqlite3.rs
index cbe9b85c6..f3eea603e 100644
--- a/crates/stdlib/src/_sqlite3.rs
+++ b/crates/stdlib/src/_sqlite3.rs
@@ -54,7 +54,7 @@ mod _sqlite3 {
     use rustpython_vm::{
         __exports::paste,
         AsObject, Py, PyAtomicRef, PyObject, PyObjectRef, PyPayload, PyRef, PyResult,
-        TryFromBorrowedObject, VirtualMachine, atomic_func,
+        TryFromBorrowedObject, TryFromObject, VirtualMachine, atomic_func,
         builtins::{
             PyBaseException, PyBaseExceptionRef, PyByteArray, PyBytes, PyDict, PyDictRef, PyFloat,
             PyInt, PyIntRef, PyModule, PySlice, PyStr, PyStrRef, PyTuple, PyTupleRef, PyType,
@@ -330,6 +330,19 @@ mod _sqlite3 {
         }
     }
 
+    struct IsolationLevelArg(Option<PyStrRef>);
+
+    impl TryFromObject for IsolationLevelArg {
+        fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
+            if vm.is_none(&obj) {
+                return Ok(Self(None));
+            }
+            obj.downcast::<PyStr>()
+                .map(|s| Self(Some(s)))
+                .map_err(|_| vm.new_type_error("isolation_level must be str or None".to_owned()))
+        }
+    }
+
     #[derive(FromArgs)]
     struct ConnectArgs {
         #[pyarg(any)]
@@ -338,8 +351,8 @@ mod _sqlite3 {
         timeout: TimeoutSeconds,
         #[pyarg(any, default = 0)]
         detect_types: c_int,
-        #[pyarg(any, default = Some(vm.ctx.empty_str.to_owned()))]
-        isolation_level: Option<PyStrRef>,
+        #[pyarg(any, default = IsolationLevelArg(Some(vm.ctx.empty_str.to_owned())))]
+        isolation_level: IsolationLevelArg,
         #[pyarg(any, default = true)]
         check_same_thread: bool,
         #[pyarg(any, default = Connection::class(&vm.ctx).to_owned())]
@@ -356,7 +369,7 @@ mod _sqlite3 {
 
     unsafe impl Traverse for ConnectArgs {
         fn traverse(&self, tracer_fn: &mut TraverseFn<'_>) {
-            self.isolation_level.traverse(tracer_fn);
+            self.isolation_level.0.traverse(tracer_fn);
             self.factory.traverse(tracer_fn);
         }
     }
@@ -914,7 +927,7 @@ mod _sqlite3 {
                 db: PyMutex::new(db),
                 initialized: Radium::new(initialized),
                 detect_types: Radium::new(args.detect_types),
-                isolation_level: PyAtomicRef::from(args.isolation_level),
+                isolation_level: PyAtomicRef::from(args.isolation_level.0),
                 check_same_thread: Radium::new(args.check_same_thread),
                 thread_ident: PyMutex::new(std::thread::current().id()),
                 row_factory: PyAtomicRef::from(None),
@@ -970,7 +983,7 @@ mod _sqlite3 {
                 .store(check_same_thread, Ordering::Relaxed);
             *zelf.autocommit.lock() = autocommit;
             *zelf.thread_ident.lock() = std::thread::current().id();
-            let _ = unsafe { zelf.isolation_level.swap(isolation_level) };
+            let _ = unsafe { zelf.isolation_level.swap(isolation_level.0) };
 
             let mut guard = zelf.db.lock();
             *guard = Some(db);
@@ -996,7 +1009,7 @@ mod _sqlite3 {
             let db = Sqlite::from(SqliteRaw::open(path.as_ptr(), args.uri, vm)?);
             let timeout = (args.timeout.to_secs_f64() * 1000.0) as c_int;
             db.busy_timeout(timeout);
-            if let Some(isolation_level) = &args.isolation_level {
+            if let Some(isolation_level) = &args.isolation_level.0 {
                 begin_statement_ptr_from_isolation_level(isolation_level, vm)?;
             }
             Ok(db)
@@ -1492,11 +1505,11 @@ mod _sqlite3 {
         #[pygetset(setter)]
         fn set_isolation_level(
             &self,
-            value: PySetterValue<Option<PyStrRef>>,
+            value: PySetterValue<IsolationLevelArg>,
             vm: &VirtualMachine,
         ) -> PyResult<()> {
             match value {
-                PySetterValue::Assign(value) => {
+                PySetterValue::Assign(IsolationLevelArg(value)) => {
                     if let Some(val_str) = &value {
                         begin_statement_ptr_from_isolation_level(val_str, vm)?;
                     }