diff -r 13b600dc4ee5 Lib/encodings/__init__.py
--- a/Lib/encodings/__init__.py	Thu Dec 15 05:38:46 2016 +0300
+++ b/Lib/encodings/__init__.py	Thu Dec 15 18:23:57 2016 +0900
@@ -26,7 +26,7 @@ Written by Marc-Andre Lemburg (mal@lembu
 
 (c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
 
-"""#"
+"""
 
 import codecs
 import sys
@@ -37,11 +37,23 @@ from . import aliases
 _import_tail = ['*']
 _aliases = aliases.aliases
 
+
+_norm_encoding_map = (
+    #0123456789ABCDEF0123456789ABCDEF
+    '                                '
+    '              . 0123456789      '
+    ' ABCDEFGHIJKLMNOPQRSTUVWXYZ     '
+    ' abcdefghijklmnopqrstuvwxyz     '
+    '                                '
+    '                                '
+    '                                '
+    '                                ')
+
+
 class CodecRegistryError(LookupError, SystemError):
     pass
 
 def normalize_encoding(encoding):
-
     """ Normalize an encoding name.
 
         Normalization works as follows: all non-alphanumeric
@@ -51,22 +63,13 @@ def normalize_encoding(encoding):
 
         Note that encoding names should be ASCII only; if they do use
         non-ASCII characters, these must be Latin-1 compatible.
-
     """
     if isinstance(encoding, bytes):
         encoding = str(encoding, "ascii")
 
-    chars = []
-    punct = False
-    for c in encoding:
-        if c.isalnum() or c == '.':
-            if punct and chars:
-                chars.append('_')
-            chars.append(c)
-            punct = False
-        else:
-            punct = True
-    return ''.join(chars)
+    s = encoding.translate(_norm_encoding_map)
+    return '_'.join(s.split())
+
 
 def search_function(encoding):