diff --git a/Lib/site.py b/Lib/site.py
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -52,6 +52,52 @@ ImportError exception, it is silently ig
 
 """
 
+def open(file, mode="r", buffering=-1, encoding=None, errors=None,
+         newline=None, closefd=True):
+    if encoding is None and 'b' not in mode:
+        import warnings
+        warnings.warn('open encoding is not set', ResourceWarning, 2)
+    elif encoding == 'locale':
+        encoding = None
+    return open.builtin(file, mode, buffering,
+                        encoding, errors, newline, closefd)
+open.builtin = __builtins__['open']
+__builtins__['open'] = open
+import io, _pyio
+io.open = open
+_pyio.open = open
+
+_cTextIOWrapper = io.TextIOWrapper
+
+class cTextIOWrapper(_cTextIOWrapper):
+    def __init__(self, buffer, encoding=None, errors=None, newline=None,
+                 line_buffering=False):
+        if encoding is None:
+            import warnings
+            warnings.warn('TextIOWrapper encoding is not set', ResourceWarning, 2)
+        elif encoding == 'locale':
+            encoding = None
+        _cTextIOWrapper.__init__(self, buffer, encoding, errors,
+                                  newline, line_buffering)
+
+io.TextIOWrapper = cTextIOWrapper
+
+_pyTextIOWrapper = _pyio.TextIOWrapper
+
+class pyTextIOWrapper(_pyTextIOWrapper):
+    def __init__(self, buffer, encoding=None, errors=None, newline=None,
+                 line_buffering=False):
+        if encoding is None:
+            import warnings
+            warnings.warn('TextIOWrapper encoding is not set', ResourceWarning, 2)
+        elif encoding == 'locale':
+            encoding = None
+        _pyTextIOWrapper.__init__(self, buffer, encoding, errors,
+                                  newline, line_buffering)
+
+_pyio.TextIOWrapper = pyTextIOWrapper
+
+
 import sys
 import os
 import builtins