diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index fe622e836ddac2..2f04fee39ab3fa 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -2722,7 +2722,7 @@ def test_constructor(self):
             t.__init__(b, encoding='utf-8\0')
         with self.assertRaises(invalid_type):
             t.__init__(b, encoding="utf-8", errors=42)
-        if support.Py_DEBUG or sys.flags.dev_mode or self.is_C:
+        if support.Py_DEBUG or sys.flags.dev_mode:
             with self.assertRaises(UnicodeEncodeError):
                 t.__init__(b, encoding="utf-8", errors='\udcfe')
         if support.Py_DEBUG or sys.flags.dev_mode: