Index: Doc/library/shelve.rst
===================================================================
--- Doc/library/shelve.rst	(revision 78145)
+++ Doc/library/shelve.rst	(working copy)
@@ -92,7 +92,7 @@
   implementation used.
 
 
-.. class:: Shelf(dict, protocol=None, writeback=False)
+.. class:: Shelf(dict, protocol=None, writeback=False, keyencoding='utf-8')
 
    A subclass of :class:`collections.MutableMapping` which stores pickled values
    in the *dict* object.
@@ -106,9 +106,12 @@
    This allows natural operations on mutable entries, but can consume much more
    memory and make sync and close take a long time.
 
+   The *keyencoding* parameter is the encoding used to encode key values
+   before they are used with the underlying dict.
 
-.. class:: BsdDbShelf(dict, protocol=None, writeback=False)
 
+.. class:: BsdDbShelf(dict, protocol=None, writeback=False, keyencoding='utf-8')
+
    A subclass of :class:`Shelf` which exposes :meth:`first`, :meth:`!next`,
    :meth:`previous`, :meth:`last` and :meth:`set_location` which are available
    in the third-party :mod:`bsddb` module from `pybsddb
@@ -116,8 +119,8 @@
    modules.  The *dict* object passed to the constructor must support those
    methods.  This is generally accomplished by calling one of
    :func:`bsddb.hashopen`, :func:`bsddb.btopen` or :func:`bsddb.rnopen`.  The
-   optional *protocol* and *writeback* parameters have the same interpretation
-   as for the :class:`Shelf` class.
+   optional *protocol*, *writeback*, and *keyencoding* parameters have the same
+   interpretation as for the :class:`Shelf` class.
 
 
 .. class:: DbfilenameShelf(filename, flag='c', protocol=None, writeback=False)
Index: Lib/shelve.py
===================================================================
--- Lib/shelve.py	(revision 78145)
+++ Lib/shelve.py	(working copy)
@@ -88,7 +88,7 @@
         self._protocol = protocol
         self.writeback = writeback
         self.cache = {}
-        self.keyencoding = "utf-8"
+        self.keyencoding = keyencoding
 
     def __iter__(self):
         for k in self.dict.keys():
Index: Lib/test/test_shelve.py
===================================================================
--- Lib/test/test_shelve.py	(revision 78145)
+++ Lib/test/test_shelve.py	(working copy)
@@ -122,6 +122,19 @@
         self.assertEqual(len(d1), 1)
         self.assertEqual(len(d2), 1)
 
+    def test_default_keyencoding_is_not_ascii(self):
+        d = {}
+        key = 'Pöp'
+        s = shelve.Shelf(d)
+        s[key] = [1]
+        self.assertIn(key.encode('utf-8'), d)
+
+    def test_nondefault_keyencoding(self):
+        d = {}
+        key = 'Pöp'
+        s = shelve.Shelf(d, keyencoding='ascii')
+        self.assertRaises(UnicodeEncodeError, s.__setitem__, key, [1])
+
     def test_writeback_also_writes_immediately(self):
         # Issue 5754
         d = {}