diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 6e5ffa9fa20..45df1f34b5f 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -725,7 +725,7 @@ class ByteArrayTest(BaseBytesTest):
         # Issue 4348.  Make sure that operations that don't mutate the array
         # copy the bytes.
         b = bytearray(b'abc')
-        #self.assertFalse(b is b.replace(b'abc', b'cde', 0))
+        self.assertFalse(b is b.replace(b'abc', b'cde', 0))
 
         t = bytearray([i for i in range(256)])
         x = bytearray(b'')