diff -r 03b5f75ddac7 Lib/pprint.py
--- a/Lib/pprint.py	Thu Jun 07 20:04:17 2012 -0400
+++ b/Lib/pprint.py	Thu Jun 07 23:28:44 2012 -0400
@@ -86,7 +86,11 @@
         self.obj = obj
 
     def __lt__(self, other):
-        rv = self.obj.__lt__(other.obj)
+        try:
+            rv = self.obj.__lt__(other.obj)
+        except TypeError:
+            rv = NotImplemented
+
         if rv is NotImplemented:
             rv = (str(type(self.obj)), id(self.obj)) < \
                  (str(type(other.obj)), id(other.obj))
diff -r 03b5f75ddac7 Lib/test/test_pprint.py
--- a/Lib/test/test_pprint.py	Thu Jun 07 20:04:17 2012 -0400
+++ b/Lib/test/test_pprint.py	Thu Jun 07 23:28:44 2012 -0400
@@ -466,6 +466,15 @@
         self.assertEqual(clean(pprint.pformat(dict.fromkeys(keys))),
             '{' + ','.join('%r:None' % k for k in skeys) + '}')
 
+        # Issue 10017: TypeError on user-defined types as dict keys.
+        self.assertEqual(pprint.pformat({Unorderable: 0, 1: 0}),
+                         '{1: 0, ' + repr(Unorderable) +': 0}')
+
+        # Issue 14998: TypeError on tuples with NoneTypes as dict keys.
+        self.assertEqual(pprint.pformat({(1,): 0, (None,): 0}),
+                         '{(1,): 0, (None,): 0}')
+
+
 class DottedPrettyPrinter(pprint.PrettyPrinter):
 
     def format(self, object, context, maxlevels, level):