diff --git a/zipline/protocol_utils.py b/zipline/protocol_utils.py
index 578cf2d5..8411ef54 100644
--- a/zipline/protocol_utils.py
+++ b/zipline/protocol_utils.py
@@ -147,7 +147,7 @@ class ndict(MutableMapping):
     def __iter__(self):
         return self.__internal.iterkeys()
 
-    def __len__(self, key):
+    def __len__(self):
         return len(self.__internal)
 
     # Compatability with namedicts
@@ -163,9 +163,15 @@ class ndict(MutableMapping):
         """
         return self.__contains__(key)
 
+    def has_key(self, key):
+        return self.__contains__(key)
+
     # Custom Methods
     # --------------
 
+    def copy(self):
+        return ndict(copy.copy(self.__internal))
+
     def as_dataframe(self):
         """
         Return the representation as a Pandas dataframe.
@@ -212,3 +218,5 @@ class ndict(MutableMapping):
                 #return False
 
         #return True
+
+namedict = ndict
diff --git a/zipline/test/test_ndict.py b/zipline/test/test_ndict.py
new file mode 100644
index 00000000..b214ac74
--- /dev/null
+++ b/zipline/test/test_ndict.py
@@ -0,0 +1,46 @@
+from zipline.protocol_utils import ndict
+
+def test_ndict():
+    nd = ndict({})
+
+    # Properties
+    assert len(nd) == 0
+    assert nd.keys() == []
+    assert nd.values() == []
+    assert list(nd.iteritems()) == []
+
+    # Accessors
+    nd['x'] = 1
+    assert nd.x == 1
+    assert nd['x'] == 1
+    assert nd.get('y') == None
+    assert nd.get('y', 'fizzpop') == 'fizzpop'
+    assert nd.has_key('x') == True
+    assert nd.has_key('y') == False
+
+    assert 'x' in nd
+    assert 'y' not in nd
+
+    # Class isolation
+    assert '__init__' not in nd
+    assert '__iter__' not in nd
+    assert not nd.__dict__.has_key('x')
+    assert nd.get('__init__') is None
+
+    # Comparison
+    nd2 = nd.copy()
+    assert id(nd2) != id(nd)
+    assert nd2 == nd
+    nd2['z'] = 3
+    assert nd2 != nd
+
+    class ndictlike(object):
+        x = 1
+
+    assert { 'x': 1 } == nd
+    assert ndictlike() != nd
+
+    # Deletion
+    del nd['x']
+    assert not nd.has_key('x')
+    assert nd.get('x') is None