diff --git a/example1.py b/example1.py
index ad4d8e9..47f8e8b 100644
--- a/example1.py
+++ b/example1.py
@@ -23,3 +23,15 @@
     'test_list': [1, 2, '3'],
 }
 test_logger.info('python-logstash: test extra fields', extra=extra)
+
+class SomeClass:
+
+    def __init__(self):
+        self.a = 1
+        self.b = 1
+
+    def __repr__(self):
+        return "Test(a={}, b={})".format(self.a, self.b)
+
+test_logger.info("test inner json: %s", SomeClass(), extra={"meta": {"test": SomeClass()}})
+
diff --git a/logstash/formatter.py b/logstash/formatter.py
index f5c4424..438ce8a 100644
--- a/logstash/formatter.py
+++ b/logstash/formatter.py
@@ -3,6 +3,9 @@
 import socket
 import sys
 from datetime import datetime
+import six
+from decimal import Decimal
+
 try:
     import json
 except ImportError:
@@ -10,6 +13,13 @@
 
 
 class LogstashFormatterBase(logging.Formatter):
+    skip_list = (
+        'args', 'asctime', 'created', 'exc_info', 'exc_text', 'filename',
+        'funcName', 'id', 'levelname', 'levelno', 'lineno', 'module',
+        'msecs', 'msecs', 'message', 'msg', 'name', 'pathname', 'process',
+        'processName', 'relativeCreated', 'thread', 'threadName', 'extra',
+        'auth_token', 'password'
+    )
 
     def __init__(self, message_type='Logstash', tags=None, fqdn=False):
         self.message_type = message_type
@@ -20,29 +30,41 @@ def __init__(self, message_type='Logstash', tags=None, fqdn=False):
         else:
             self.host = socket.gethostname()
 
+    def _serialize_value(self, value):
+        # Recursively serializes value
+
+        if isinstance(value, dict):
+            return {
+                key: self._serialize_value(item)
+                for key, item in six.iteritems(value)
+            }
+        elif isinstance(value, (set, tuple, list, frozenset)):
+            return [
+                self._serialize_value(item)
+                for item in value
+            ]
+        else:
+            if sys.version_info < (3, 0):
+                easy_types = (basestring, bool, dict, float, int, long, list, type(None))
+            else:
+                easy_types = (str, bool, dict, float, int, list, type(None))
+
+            if isinstance(value, easy_types):
+                return value
+            elif isinstance(value, Decimal):
+                return float(value)
+            else:
+                return repr(value)
+
     def get_extra_fields(self, record):
         # The list contains all the attributes listed in
         # http://docs.python.org/library/logging.html#logrecord-attributes
-        skip_list = (
-            'args', 'asctime', 'created', 'exc_info', 'exc_text', 'filename',
-            'funcName', 'id', 'levelname', 'levelno', 'lineno', 'module',
-            'msecs', 'msecs', 'message', 'msg', 'name', 'pathname', 'process',
-            'processName', 'relativeCreated', 'thread', 'threadName', 'extra',
-            'auth_token', 'password')
-
-        if sys.version_info < (3, 0):
-            easy_types = (basestring, bool, dict, float, int, long, list, type(None))
-        else:
-            easy_types = (str, bool, dict, float, int, list, type(None))
 
         fields = {}
 
         for key, value in record.__dict__.items():
-            if key not in skip_list:
-                if isinstance(value, easy_types):
-                    fields[key] = value
-                else:
-                    fields[key] = repr(value)
+            if key not in self.skip_list:
+                fields[key] = self._serialize_value(value)
 
         return fields
 
@@ -140,3 +162,4 @@ def format(self, record):
             message.update(self.get_debug_fields(record))
 
         return self.serialize(message)
+
diff --git a/logstash/handler_tcp.py b/logstash/handler_tcp.py
index cc687bd..07e2ceb 100644
--- a/logstash/handler_tcp.py
+++ b/logstash/handler_tcp.py
@@ -1,9 +1,12 @@
 from logging.handlers import DatagramHandler, SocketHandler
-from logstash import formatter
 
 
 # Derive from object to force a new-style class and thus allow super() to work
 # on Python 2.6
+from logstash import LogstashFormatterVersion0
+from logstash import LogstashFormatterVersion1
+
+
 class TCPLogstashHandler(SocketHandler, object):
     """Python logging handler for Logstash. Sends events over TCP.
     :param host: The host of the logstash server.
@@ -12,14 +15,21 @@ class TCPLogstashHandler(SocketHandler, object):
     :param fqdn; Indicates whether to show fully qualified domain name or not (default False).
     :param version: version of logstash event schema (default is 0).
     :param tags: list of tags for a logger (default is None).
+    :param fmt: custom formatter instance
     """
 
-    def __init__(self, host, port=5959, message_type='logstash', tags=None, fqdn=False, version=0):
+    def __init__(self, host, port=5959, message_type='logstash', tags=None, fqdn=False, version=0,
+                 formatterCls=None):
         super(TCPLogstashHandler, self).__init__(host, port)
-        if version == 1:
-            self.formatter = formatter.LogstashFormatterVersion1(message_type, tags, fqdn)
+
+        if not formatterCls:
+            if version == 1:
+                self.formatter = LogstashFormatterVersion1(message_type, tags, fqdn)
+            else:
+                self.formatter = LogstashFormatterVersion0(message_type, tags, fqdn)
         else:
-            self.formatter = formatter.LogstashFormatterVersion0(message_type, tags, fqdn)
+            self.formatter = formatterCls(message_type, tags, fqdn)
+
 
     def makePickle(self, record):
         return self.formatter.format(record) + b'\n'
diff --git a/setup.py b/setup.py
index 3329e91..a58aa18 100644
--- a/setup.py
+++ b/setup.py
@@ -1,8 +1,10 @@
-from distutils.core import setup
+from setuptools import setup
+
 setup(
     name='python-logstash',
     packages=['logstash'],
     version='0.4.7',
+    install_requires=["six"],
     description='Python logging handler for Logstash.',
     long_description=open('README.rst').read(),
     license='MIT',