diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index 4a7230f6711298..b4a52a53105eda 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -630,6 +630,7 @@ def check_different_constants(const1, const2):
             f1 = ns['f1']
             f2 = ns['f2']
             self.assertIsNot(f1.__code__, f2.__code__)
+            self.assertNotEqual(f1.__code__, f2.__code__)
             self.check_constant(f1, const1)
             self.check_constant(f2, const2)
             self.assertEqual(repr(f1()), repr(const1))
@@ -638,6 +639,8 @@ def check_different_constants(const1, const2):
         check_different_constants(0, 0.0)
         check_different_constants(+0.0, -0.0)
         check_different_constants((0,), (0.0,))
+        check_different_constants('a', b'a')
+        check_different_constants(('a',), (b'a',))
 
         # check_different_constants() cannot be used because repr(-0j) is
         # '(-0-0j)', but when '(-0-0j)' is evaluated to 0j: we loose the sign.
diff --git a/Misc/NEWS b/Misc/NEWS
index b8218fbcb52a35..6ce2e3d791cc02 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.7.0 alpha 1?
 Core and Builtins
 -----------------
 
+- Issue #29337: Fixed possible BytesWarning when compare the code objects.
+  Warnings could be emitted at compile time.
+
 - Issue #29327: Fixed a crash when pass the iterable keyword argument to
   sorted().
 
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index 0857554adc3bae..b1e8ec9f09bab3 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -550,7 +550,7 @@ _PyCode_ConstantKey(PyObject *op)
             PyTuple_SET_ITEM(tuple, i, item_key);
         }
 
-        key = PyTuple_Pack(3, Py_TYPE(op), op, tuple);
+        key = PyTuple_Pack(2, tuple, op);
         Py_DECREF(tuple);
     }
     else if (PyFrozenSet_CheckExact(op)) {
@@ -584,7 +584,7 @@ _PyCode_ConstantKey(PyObject *op)
         if (set == NULL)
             return NULL;
 
-        key = PyTuple_Pack(3, Py_TYPE(op), op, set);
+        key = PyTuple_Pack(2, set, op);
         Py_DECREF(set);
         return key;
     }
@@ -595,7 +595,7 @@ _PyCode_ConstantKey(PyObject *op)
         if (obj_id == NULL)
             return NULL;
 
-        key = PyTuple_Pack(3, Py_TYPE(op), op, obj_id);
+        key = PyTuple_Pack(2, obj_id, op);
         Py_DECREF(obj_id);
     }
     return key;