diff --git a/README.md b/README.md
index 5f94596..0175e4b 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@ import json
 
 test_instance = Test('foo')
 blob = Marshal.marshal(test_instance)
-print(blob)
+print(blob.decode())
 >>> '{name: foo}'
 
 marshal = Marshal()
@@ -101,7 +101,7 @@ class TestContainer:
 marshal = Marshal()
 container_instance = TestContainer({'foo', 'bar'})        
 blob = marshal.marshal(container_instance)
-print(blob)
+print(blob.decode())
 >>> '{container: ["foo", "bar"]}'
 
 result = marshal.unmarshal(TestContainer,json.loads(blob))
@@ -190,5 +190,5 @@ print(result.message_obj)
 >>> 'Hello from the custom delegate!'
 ```
 
-The result from any delegate should be initialized resulting class instance
+The result from any delegate should be the initialized resulting class instance
 
diff --git a/pymarshaler/__init__.py b/pymarshaler/__init__.py
index 3533191..8804a29 100644
--- a/pymarshaler/__init__.py
+++ b/pymarshaler/__init__.py
@@ -1,4 +1,4 @@
-__version__ = '0.3.0'
+__version__ = '0.3.1'
 __all__ = ['Marshal', 'utils', 'arg_delegates', 'errors']
 
 from pymarshaler.marshal import Marshal
diff --git a/pymarshaler/arg_delegates.py b/pymarshaler/arg_delegates.py
index 4436aed..910ae66 100644
--- a/pymarshaler/arg_delegates.py
+++ b/pymarshaler/arg_delegates.py
@@ -28,9 +28,9 @@ def resolve(self, data):
 
 class EnumArgBuilderDelegate(ArgBuilderDelegate):
 
-    def resolve(self, data: str):
-        for k, v in self.cls.__members__.items():
-            if k == data.upper():
+    def resolve(self, data):
+        for v in self.cls.__members__.values():
+            if v.value == data:
                 return v
         raise UnknownFieldError(f'Invalid value {data} for enum {self.cls.__name__}')
 
diff --git a/pymarshaler/marshal.py b/pymarshaler/marshal.py
index ff65838..fff6c0b 100644
--- a/pymarshaler/marshal.py
+++ b/pymarshaler/marshal.py
@@ -1,11 +1,9 @@
 import datetime
 import inspect
-import json
 import typing
 from enum import Enum
-from json import JSONEncoder
 
-import jsonpickle
+import orjson
 
 from pymarshaler.arg_delegates import ArgBuilderDelegate, ListArgBuilderDelegate, \
     SetArgBuilderDelegate, TupleArgBuilderDelegate, DictArgBuilderDelegate, BuiltinArgBuilderDelegate, \
@@ -81,16 +79,11 @@ def _safe_get(self, name):
         return self._default_arg_builder_delegates[name]
 
 
-class _DictEncoder(JSONEncoder):
-    def default(self, o):
-        if isinstance(o, datetime.datetime):
-            return o.isoformat()
-        elif isinstance(o, Enum):
-            return o.name
-        try:
-            return o.__dict__
-        except AttributeError:
-            return repr(o)
+def _default(o):
+    try:
+        return o.__dict__
+    except AttributeError:
+        return repr(o)
 
 
 class Marshal:
@@ -106,11 +99,10 @@ def __init__(self, ignore_unknown_fields: bool = False, walk_unknown_fields: boo
         )
 
     @staticmethod
-    def marshal(obj, indent=2) -> str:
+    def marshal(obj) -> bytes:
         """
         Convert a class instance to a JSON formatted string
         :param obj: The object to convert
-        :param indent: How to format the JSON. Defaults to an indent of 2
         :return: String JSON representation of the class instance
         Example:
         >>> class Test:
@@ -121,7 +113,7 @@ def marshal(obj, indent=2) -> str:
         >>> print(data)
         '{name: foo}'
         """
-        return json.dumps(obj, cls=_DictEncoder, indent=indent)
+        return orjson.dumps(obj, default=_default)
 
     def unmarshal_str(self, cls, data: str):
         """
@@ -143,7 +135,7 @@ def unmarshal_str(self, cls, data: str):
         >>> print(test_instance.name)
         'foo'
         """
-        return self.unmarshal(cls, json.loads(data))
+        return self.unmarshal(cls, orjson.loads(data))
 
     def unmarshal(self, cls, data: dict):
         """
diff --git a/requirements.txt b/requirements.txt
index 2f522cc..f826a90 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,4 @@
-jsonpickle
-python-dateutil
\ No newline at end of file
+python-dateutil
+pymarshaler
+setuptools
+orjson
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 0ddba32..eb730ba 100644
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@
 
 setuptools.setup(
     name="pymarshaler",
-    version="0.3.0",
+    version='0.3.1',
     author="Hernan Romer",
     author_email="nanug33@gmail.com",
     description="Package to marshal and unmarshal python objects",