diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index b3fc042..ad04613 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -451,7 +451,7 @@
 
         # These are just dummy values but we nevertheless check them for fear
         # of unexpected breakage.
-        self.assertEqual(memio.encoding, "utf-8")
+        self.assertTrue(memio.encoding is None)
         self.assertEqual(memio.errors, "strict")
         self.assertEqual(memio.line_buffering, False)