diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index b4efa65..3e88168 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -523,8 +523,8 @@
     @test_support.cpython_only
     def test_sizeof(self):
         BLOCKLEN = 62
-        basesize = test_support.calcobjsize('2P4PlP')
-        blocksize = struct.calcsize('2P%dP' % BLOCKLEN)
+        basesize = test_support.calcobjsize('2P3PlPP')
+        blocksize = struct.calcsize('%dP2P' % BLOCKLEN)
         self.assertEqual(object.__sizeof__(deque()), basesize)
         check = self.check_sizeof
         check(deque(), basesize + blocksize)