diff --git a/logstash/formatter.py b/logstash/formatter.py
index 2b5d618..ce0ba5a 100644
--- a/logstash/formatter.py
+++ b/logstash/formatter.py
@@ -79,10 +79,8 @@ def format_exception(cls, exc_info):
 
     @classmethod
     def serialize(cls, message):
-        if sys.version_info < (3, 0):
-            return json.dumps(message)
-        else:
-            return bytes(json.dumps(message, default=str), 'utf-8')
+        return json.dumps(message)
+
 
 class LogstashFormatterVersion0(LogstashFormatterBase):
     version = 0