diff --git a/Lib/ctypes/__init__.py b/Lib/ctypes/__init__.py
index 042bc47..eb47532 100644
--- a/Lib/ctypes/__init__.py
+++ b/Lib/ctypes/__init__.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 """create and manipulate C data types in Python"""
 
 import os as _os, sys as _sys
diff --git a/Lib/ctypes/_endian.py b/Lib/ctypes/_endian.py
index 5818ae1..6de0d47 100644
--- a/Lib/ctypes/_endian.py
+++ b/Lib/ctypes/_endian.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 import sys
 from ctypes import *
 
diff --git a/Lib/ctypes/macholib/__init__.py b/Lib/ctypes/macholib/__init__.py
index 5621def..36149d2 100644
--- a/Lib/ctypes/macholib/__init__.py
+++ b/Lib/ctypes/macholib/__init__.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 """
 Enough Mach-O to make your head spin.
 
diff --git a/Lib/ctypes/macholib/dyld.py b/Lib/ctypes/macholib/dyld.py
index a336fd0..14e2139 100644
--- a/Lib/ctypes/macholib/dyld.py
+++ b/Lib/ctypes/macholib/dyld.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 """
 dyld emulation
 """
diff --git a/Lib/ctypes/macholib/dylib.py b/Lib/ctypes/macholib/dylib.py
index aa10750..ea3dd38 100644
--- a/Lib/ctypes/macholib/dylib.py
+++ b/Lib/ctypes/macholib/dylib.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 """
 Generic dylib path manipulation
 """
diff --git a/Lib/ctypes/macholib/framework.py b/Lib/ctypes/macholib/framework.py
index ad6ed55..dd7fb2f 100644
--- a/Lib/ctypes/macholib/framework.py
+++ b/Lib/ctypes/macholib/framework.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 """
 Generic framework path manipulation
 """
diff --git a/Lib/ctypes/util.py b/Lib/ctypes/util.py
index 094b029..d4e314a 100644
--- a/Lib/ctypes/util.py
+++ b/Lib/ctypes/util.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 import sys, os
 
 # find_library(name) returns the pathname of a library, or None.
diff --git a/Lib/ctypes/wintypes.py b/Lib/ctypes/wintypes.py
index 92b79d2..870d917 100644
--- a/Lib/ctypes/wintypes.py
+++ b/Lib/ctypes/wintypes.py
@@ -1,3 +1,6 @@
+######################################################################
+#  This file should be kept compatible with Python 2.3, see PEP 291. #
+######################################################################
 # XXX This module needs cleanup.
 
 from ctypes import *
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 5d29cda..4b07591 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -1,3 +1,8 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
+
 /*
   ToDo:
 
diff --git a/Modules/_ctypes/_ctypes_test.c b/Modules/_ctypes/_ctypes_test.c
index b10d6fe..99cc7a9 100644
--- a/Modules/_ctypes/_ctypes_test.c
+++ b/Modules/_ctypes/_ctypes_test.c
@@ -1,3 +1,8 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
+
 #include <Python.h>
 
 /*
diff --git a/Modules/_ctypes/callbacks.c b/Modules/_ctypes/callbacks.c
index 4baf3aa..b4f09e0 100644
--- a/Modules/_ctypes/callbacks.c
+++ b/Modules/_ctypes/callbacks.c
@@ -1,3 +1,7 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
 #include "Python.h"
 #include "compile.h" /* required only for 2.3, as it seems */
 #include "frameobject.h"
diff --git a/Modules/_ctypes/callproc.c b/Modules/_ctypes/callproc.c
index c4942a0..c229106 100644
--- a/Modules/_ctypes/callproc.c
+++ b/Modules/_ctypes/callproc.c
@@ -1,3 +1,8 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
+
 /*
  * History: First version dated from 3/97, derived from my SCMLIB version
  * for win16.
diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
index ae0290f..68fac67 100644
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -1,3 +1,7 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
 #include "Python.h"
 
 #include <ffi.h>
diff --git a/Modules/_ctypes/ctypes.h b/Modules/_ctypes/ctypes.h
index e82ff0d..6db7015 100644
--- a/Modules/_ctypes/ctypes.h
+++ b/Modules/_ctypes/ctypes.h
@@ -1,4 +1,6 @@
-/******************************************************************/
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
 
 #if (PY_VERSION_HEX < 0x02050000)
 typedef int Py_ssize_t;
diff --git a/Modules/_ctypes/ctypes_dlfcn.h b/Modules/_ctypes/ctypes_dlfcn.h
index 7f632c5..d8bf904 100644
--- a/Modules/_ctypes/ctypes_dlfcn.h
+++ b/Modules/_ctypes/ctypes_dlfcn.h
@@ -1,4 +1,6 @@
-/******************************************************************/
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
 
 #ifndef _CTYPES_DLFCN_H_
 #define _CTYPES_DLFCN_H_
diff --git a/Modules/_ctypes/malloc_closure.c b/Modules/_ctypes/malloc_closure.c
index 29e9f4c..4cd5dd6 100644
--- a/Modules/_ctypes/malloc_closure.c
+++ b/Modules/_ctypes/malloc_closure.c
@@ -1,3 +1,7 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
 #include <Python.h>
 #include <ffi.h>
 #ifdef MS_WIN32
diff --git a/Modules/_ctypes/stgdict.c b/Modules/_ctypes/stgdict.c
index 2e7e157..1ddbf85 100644
--- a/Modules/_ctypes/stgdict.c
+++ b/Modules/_ctypes/stgdict.c
@@ -1,3 +1,7 @@
+/*****************************************************************
+  This file should be kept compatible with Python 2.3, see PEP 291.
+ *****************************************************************/
+
 #include "Python.h"
 #include <ffi.h>
 #ifdef MS_WIN32