diff --git a/src/registry.py b/src/registry.py
index 1981fca42..abd074176 100644
--- a/src/registry.py
+++ b/src/registry.py
@@ -32,6 +32,7 @@ import re
 import os
 import sys
 import time
+import json
 import codecs
 import string
 import textwrap
@@ -678,4 +679,11 @@ class TemplatedString(String):
         else:
             self.error()
 
+class Json(String):
+    # Json-serializable data
+    def setValue(self, v):
+        super(Json, self).setValue(json.dumps(v))
+    def __call__(self):
+        return json.loads(super(Json, self).__call__())
+
 # vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:
diff --git a/test/test_registry.py b/test/test_registry.py
index 9a8826ace..9e8bafb85 100644
--- a/test/test_registry.py
+++ b/test/test_registry.py
@@ -130,6 +130,14 @@ class ValuesTestCase(SupyTestCase):
         v.set('"xyzzy')
         self.assertEqual(v(), '"xyzzy')
 
+    def testJson(self):
+        data = {'foo': ['bar', 'baz', 5], 'qux': None}
+        v = registry.Json('foo', 'help')
+        self.assertEqual(v(), 'foo')
+        v.setValue(data)
+        self.assertEqual(v(), data)
+        self.assertIsNot(v(), data)
+
     def testNormalizedString(self):
         v = registry.NormalizedString("""foo
         bar           baz