diff --git a/python/msgpack/_msgpack.pyx b/python/msgpack/_msgpack.pyx
index 24e4f8b9..0abdd515 100644
--- a/python/msgpack/_msgpack.pyx
+++ b/python/msgpack/_msgpack.pyx
@@ -80,7 +80,7 @@ cdef class Packer(object):
     def __dealloc__(self):
         free(self.pk.buf);
 
-    cdef int _pack(self, object o) except -1:
+    cdef int _pack(self, object o, int nest_limit=511, default=None) except -1:
         cdef long long llval
         cdef unsigned long long ullval
         cdef long longval
@@ -89,6 +89,9 @@ cdef class Packer(object):
         cdef int ret
         cdef dict d
 
+        if nest_limit < 0:
+            raise ValueError("Too deep.")
+
         if o is None:
             ret = msgpack_pack_nil(&self.pk)
             #elif PyBool_Check(o):
@@ -126,33 +129,26 @@ cdef class Packer(object):
             ret = msgpack_pack_map(&self.pk, len(d))
             if ret == 0:
                 for k,v in d.items():
-                    ret = self._pack(k)
+                    ret = self._pack(k, nest_limit-1, default)
                     if ret != 0: break
-                    ret = self._pack(v)
+                    ret = self._pack(v, nest_limit-1, default)
                     if ret != 0: break
         elif PySequence_Check(o):
             ret = msgpack_pack_array(&self.pk, len(o))
             if ret == 0:
                 for v in o:
-                    ret = self._pack(v)
+                    ret = self._pack(v, nest_limit-1, default)
                     if ret != 0: break
-        elif self.default is not None:
+        elif default is not None:
             o = self.default(o)
-            d = o
-            ret = msgpack_pack_map(&self.pk, len(d))
-            if ret == 0:
-                for k,v in d.items():
-                    ret = self._pack(k)
-                    if ret != 0: break
-                    ret = self._pack(v)
-                    if ret != 0: break
+            ret = self._pack(o, nest_limit)
         else:
             raise TypeError("can't serialize %r" % (o,))
         return ret
 
     def pack(self, object obj):
         cdef int ret
-        ret = self._pack(obj)
+        ret = self._pack(obj, self.default)
         if ret:
             raise TypeError
         buf = PyBytes_FromStringAndSize(self.pk.buf, self.pk.length)
diff --git a/python/test/test_obj.py b/python/test/test_obj.py
index 64a63903..28edacb8 100644
--- a/python/test/test_obj.py
+++ b/python/test/test_obj.py
@@ -26,6 +26,12 @@ def test_decode_hook():
     unpacked = unpacks(packed, object_hook=_decode_complex)
     eq_(unpacked[1], 1+2j)
 
+@raises(TypeError)
+def test_bad_hook():
+    packed = packs([3, 1+2j], default=lambda o: o)
+    unpacked = unpacks(packed)
+
 if __name__ == '__main__':
-    #main()
     test_decode_hook()
+    test_encode_hook()
+    test_bad_hook()