diff -r 44f455e6163d Lib/argparse.py
--- a/Lib/argparse.py	Thu Jun 27 12:23:29 2013 +0200
+++ b/Lib/argparse.py	Sat Jul 12 14:47:38 2014 -0700
@@ -1263,7 +1263,11 @@
         registry[value] = object
 
     def _registry_get(self, registry_name, value, default=None):
-        return self._registries[registry_name].get(value, default)
+        try:
+            return self._registries[registry_name].get(value, default)
+        except TypeError:
+            # probably TypeError: unhashable type: 'dict', e.g. {}.get
+            return default
 
     # ==================================
     # Namespace default accessor methods
diff -r 44f455e6163d Lib/test/test_argparse.py
--- a/Lib/test/test_argparse.py	Thu Jun 27 12:23:29 2013 +0200
+++ b/Lib/test/test_argparse.py	Sat Jul 12 14:47:38 2014 -0700
@@ -4672,6 +4672,30 @@
         args = parser.parse_args([])
         self.assertEqual(args.test, [])
 
+# =======================
+# unhashable type tests
+# =======================
+
+class TestUnhasableTypeError(TestCase):
+
+    @unittest.skip('corrected with _registry_get change')
+    def test_unhashable_type_error(self):
+        "error with original code"
+        dd = dict(one=1, two=20, three=300)
+        parser = ErrorRaisingArgumentParser(prog='PROG', add_help=False)
+        with self.assertRaises(TypeError) as cm:
+            parser.add_argument('x', type=dd.get)
+        msg = str(cm.exception)
+        self.assertRegex(msg, 'unhashable type')
+
+    def test_unhashable_type_noerror(self):
+        "_registry_get handles unhashable TypeError"
+        dd = dict(one=1, two=20, three=300)
+        parser = ErrorRaisingArgumentParser(prog='PROG', add_help=False)
+        parser.add_argument('x', type=dd.get)
+        args = parser.parse_args('two'.split())
+        self.assertEqual(NS(x=20), args)
+
 # ======================
 # parse_known_args tests
 # ======================