diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 951358791..05eeb846d 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1896,8 +1896,6 @@ class UnicodeTest(string_tests.CommonTest,
         self.assertEqual((b'aaaa' + seq + b'bbbb').decode('utf-8', 'ignore'),
                           'aaaa' + res + 'bbbb')
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_invalid_start_byte(self):
         """
         Test that an 'invalid start byte' error is raised when the first byte
diff --git a/common/src/encodings.rs b/common/src/encodings.rs
index fbe5aed3c..83cbcace6 100644
--- a/common/src/encodings.rs
+++ b/common/src/encodings.rs
@@ -89,7 +89,7 @@ pub mod utf8 {
                     let err_idx = remaining_index + e.valid_up_to();
                     remaining_data = rest;
                     remaining_index += valid_prefix.len();
-                    if (0x80..0xc0).contains(&first_err) {
+                    if (0x80..0xc2).contains(&first_err) || (0xf5..=0xff).contains(&first_err) {
                         handle_error!(err_idx..err_idx + 1, "invalid start byte");
                     }
                     let err_len = match e.error_len() {