diff --git a/nyoibo/entities/entity.c b/nyoibo/entities/entity.c
index fc7edc6..955c085 100644
--- a/nyoibo/entities/entity.c
+++ b/nyoibo/entities/entity.c
@@ -900,10 +900,6 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_GetAttrStr(PyObject* obj, PyObject
 /* GetBuiltinName.proto */
 static PyObject *__Pyx_GetBuiltinName(PyObject *name);
 
-/* RaiseArgTupleInvalid.proto */
-static void __Pyx_RaiseArgtupleInvalid(const char* func_name, int exact,
-    Py_ssize_t num_min, Py_ssize_t num_max, Py_ssize_t num_found);
-
 /* RaiseDoubleKeywords.proto */
 static void __Pyx_RaiseDoubleKeywordsError(const char* func_name, PyObject* kw_name);
 
@@ -912,6 +908,10 @@ static int __Pyx_ParseOptionalKeywords(PyObject *kwds, PyObject **argnames[],\
     PyObject *kwds2, PyObject *values[], Py_ssize_t num_pos_args,\
     const char* function_name);
 
+/* RaiseArgTupleInvalid.proto */
+static void __Pyx_RaiseArgtupleInvalid(const char* func_name, int exact,
+    Py_ssize_t num_min, Py_ssize_t num_max, Py_ssize_t num_found);
+
 /* PyObjectSetAttrStr.proto */
 #if CYTHON_USE_TYPE_SLOTS
 #define __Pyx_PyObject_DelAttrStr(o,n) __Pyx_PyObject_SetAttrStr(o, n, NULL)
@@ -1093,6 +1093,9 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_CallMethO(PyObject *func, PyObject
 /* PyObjectCallOneArg.proto */
 static CYTHON_INLINE PyObject* __Pyx_PyObject_CallOneArg(PyObject *func, PyObject *arg);
 
+/* PyObjectCall2Args.proto */
+static CYTHON_UNUSED PyObject* __Pyx_PyObject_Call2Args(PyObject* function, PyObject* arg1, PyObject* arg2);
+
 /* CalculateMetaclass.proto */
 static PyObject *__Pyx_CalculateMetaclass(PyTypeObject *metaclass, PyObject *bases);
 
@@ -1210,6 +1213,7 @@ static const char __pyx_k_value[] = "value";
 static const char __pyx_k_Entity[] = "Entity";
 static const char __pyx_k_import[] = "__import__";
 static const char __pyx_k_module[] = "__module__";
+static const char __pyx_k_setter[] = "setter";
 static const char __pyx_k_prepare[] = "__prepare__";
 static const char __pyx_k_value_2[] = "_value";
 static const char __pyx_k_property[] = "property";
@@ -1241,21 +1245,26 @@ static PyObject *__pyx_n_s_prepare;
 static PyObject *__pyx_n_s_property;
 static PyObject *__pyx_n_s_qualname;
 static PyObject *__pyx_n_s_self;
+static PyObject *__pyx_n_s_setter;
 static PyObject *__pyx_n_s_test;
 static PyObject *__pyx_n_s_value;
 static PyObject *__pyx_n_s_value_2;
 static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity___init__(CYTHON_UNUSED PyObject *__pyx_self, PyObject *__pyx_v_self, PyObject *__pyx_v_value); /* proto */
 static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity_2value(CYTHON_UNUSED PyObject *__pyx_self, PyObject *__pyx_v_self); /* proto */
+static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity_4value(CYTHON_UNUSED PyObject *__pyx_self, PyObject *__pyx_v_self, PyObject *__pyx_v_value); /* proto */
 static PyObject *__pyx_tuple_;
 static PyObject *__pyx_tuple__3;
+static PyObject *__pyx_tuple__4;
+static PyObject *__pyx_tuple__6;
 static PyObject *__pyx_codeobj__2;
-static PyObject *__pyx_codeobj__4;
+static PyObject *__pyx_codeobj__5;
+static PyObject *__pyx_codeobj__7;
 /* Late includes */
 
 /* "nyoibo/entities/entity.pyx":6
  * class Entity(metaclass=MetaEntity):
  *
- *     def __init__(self, value):             # <<<<<<<<<<<<<<
+ *     def __init__(self, value=None):             # <<<<<<<<<<<<<<
  *         self._value = value
  *
  */
@@ -1275,6 +1284,7 @@ static PyObject *__pyx_pw_6nyoibo_8entities_6entity_6Entity_1__init__(PyObject *
   {
     static PyObject **__pyx_pyargnames[] = {&__pyx_n_s_self,&__pyx_n_s_value,0};
     PyObject* values[2] = {0,0};
+    values[1] = ((PyObject *)((PyObject *)Py_None));
     if (unlikely(__pyx_kwds)) {
       Py_ssize_t kw_args;
       const Py_ssize_t pos_args = PyTuple_GET_SIZE(__pyx_args);
@@ -1293,26 +1303,29 @@ static PyObject *__pyx_pw_6nyoibo_8entities_6entity_6Entity_1__init__(PyObject *
         else goto __pyx_L5_argtuple_error;
         CYTHON_FALLTHROUGH;
         case  1:
-        if (likely((values[1] = __Pyx_PyDict_GetItemStr(__pyx_kwds, __pyx_n_s_value)) != 0)) kw_args--;
-        else {
-          __Pyx_RaiseArgtupleInvalid("__init__", 1, 2, 2, 1); __PYX_ERR(0, 6, __pyx_L3_error)
+        if (kw_args > 0) {
+          PyObject* value = __Pyx_PyDict_GetItemStr(__pyx_kwds, __pyx_n_s_value);
+          if (value) { values[1] = value; kw_args--; }
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-    } else if (PyTuple_GET_SIZE(__pyx_args) != 2) {
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     } else {
-      values[0] = PyTuple_GET_ITEM(__pyx_args, 0);
-      values[1] = PyTuple_GET_ITEM(__pyx_args, 1);
+      switch (PyTuple_GET_SIZE(__pyx_args)) {
+        case  2: values[1] = PyTuple_GET_ITEM(__pyx_args, 1);
+        CYTHON_FALLTHROUGH;
+        case  1: values[0] = PyTuple_GET_ITEM(__pyx_args, 0);
+        break;
+        default: goto __pyx_L5_argtuple_error;
+      }
     }
     __pyx_v_self = values[0];
     __pyx_v_value = values[1];
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   __pyx_L5_argtuple_error:;
-  __Pyx_RaiseArgtupleInvalid("__init__", 1, 2, 2, PyTuple_GET_SIZE(__pyx_args)); __PYX_ERR(0, 6, __pyx_L3_error)
+  __Pyx_RaiseArgtupleInvalid("__init__", 0, 1, 2, PyTuple_GET_SIZE(__pyx_args)); __PYX_ERR(0, 6, __pyx_L3_error)
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@@ -1335,7 +1348,7 @@ static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity___init__(CYTHON_UNUS
 
   /* "nyoibo/entities/entity.pyx":7
  *
- *     def __init__(self, value):
+ *     def __init__(self, value=None):
  *         self._value = value             # <<<<<<<<<<<<<<
  *
  *     @property
@@ -1345,7 +1358,7 @@ static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity___init__(CYTHON_UNUS
   /* "nyoibo/entities/entity.pyx":6
  * class Entity(metaclass=MetaEntity):
  *
- *     def __init__(self, value):             # <<<<<<<<<<<<<<
+ *     def __init__(self, value=None):             # <<<<<<<<<<<<<<
  *         self._value = value
  *
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@@ -1367,6 +1380,7 @@ static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity___init__(CYTHON_UNUS
  *     @property
  *     def value(self):             # <<<<<<<<<<<<<<
  *         return self._value
+ *
  */
 
 /* Python wrapper */
@@ -1396,6 +1410,8 @@ static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity_2value(CYTHON_UNUSED
  *     @property
  *     def value(self):
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+ *     @value.setter
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  *     @property
  *     def value(self):             # <<<<<<<<<<<<<<
  *         return self._value
+ *
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   /* function exit code */
@@ -1422,6 +1439,112 @@ static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity_2value(CYTHON_UNUSED
   return __pyx_r;
 }
 
+/* "nyoibo/entities/entity.pyx":14
+ *
+ *     @value.setter
+ *     def value(self, value):             # <<<<<<<<<<<<<<
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+ */
+
+/* Python wrapper */
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+static PyObject *__pyx_pw_6nyoibo_8entities_6entity_6Entity_5value(PyObject *__pyx_self, PyObject *__pyx_args, PyObject *__pyx_kwds) {
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+  PyObject *__pyx_v_value = 0;
+  int __pyx_lineno = 0;
+  const char *__pyx_filename = NULL;
+  int __pyx_clineno = 0;
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+  __Pyx_RefNannyDeclarations
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+      values[1] = PyTuple_GET_ITEM(__pyx_args, 1);
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+  __Pyx_RaiseArgtupleInvalid("value", 1, 2, 2, PyTuple_GET_SIZE(__pyx_args)); __PYX_ERR(0, 14, __pyx_L3_error)
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+  __Pyx_AddTraceback("nyoibo.entities.entity.Entity.value", __pyx_clineno, __pyx_lineno, __pyx_filename);
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+  __Pyx_RefNannyFinishContext();
+  return __pyx_r;
+}
+
+static PyObject *__pyx_pf_6nyoibo_8entities_6entity_6Entity_4value(CYTHON_UNUSED PyObject *__pyx_self, PyObject *__pyx_v_self, PyObject *__pyx_v_value) {
+  PyObject *__pyx_r = NULL;
+  __Pyx_RefNannyDeclarations
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+ *
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+ */
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+  /* function exit code */
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 static PyMethodDef __pyx_methods[] = {
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+  {&__pyx_n_s_setter, __pyx_k_setter, sizeof(__pyx_k_setter), 0, 0, 1, 1},
   {&__pyx_n_s_test, __pyx_k_test, sizeof(__pyx_k_test), 0, 0, 1, 1},
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+    __Pyx_GetModuleGlobalName(__pyx_t_4, __pyx_n_s_value);
+  }
+  if (unlikely(!__pyx_t_4)) __PYX_ERR(0, 13, __pyx_L1_error)
+  __Pyx_GOTREF(__pyx_t_4);
+  __pyx_t_6 = __Pyx_PyObject_GetAttrStr(__pyx_t_4, __pyx_n_s_setter); if (unlikely(!__pyx_t_6)) __PYX_ERR(0, 13, __pyx_L1_error)
+  __Pyx_GOTREF(__pyx_t_6);
+  __Pyx_DECREF(__pyx_t_4); __pyx_t_4 = 0;
+
+  /* "nyoibo/entities/entity.pyx":14
+ *
+ *     @value.setter
+ *     def value(self, value):             # <<<<<<<<<<<<<<
+ *         self._value = value
+ */
+  __pyx_t_4 = __Pyx_CyFunction_New(&__pyx_mdef_6nyoibo_8entities_6entity_6Entity_5value, 0, __pyx_n_s_Entity_value, NULL, __pyx_n_s_nyoibo_entities_entity, __pyx_d, ((PyObject *)__pyx_codeobj__7)); if (unlikely(!__pyx_t_4)) __PYX_ERR(0, 14, __pyx_L1_error)
+  __Pyx_GOTREF(__pyx_t_4);
+  __pyx_t_7 = NULL;
+  if (CYTHON_UNPACK_METHODS && unlikely(PyMethod_Check(__pyx_t_6))) {
+    __pyx_t_7 = PyMethod_GET_SELF(__pyx_t_6);
+    if (likely(__pyx_t_7)) {
+      PyObject* function = PyMethod_GET_FUNCTION(__pyx_t_6);
+      __Pyx_INCREF(__pyx_t_7);
+      __Pyx_INCREF(function);
+      __Pyx_DECREF_SET(__pyx_t_6, function);
+    }
+  }
+  __pyx_t_5 = (__pyx_t_7) ? __Pyx_PyObject_Call2Args(__pyx_t_6, __pyx_t_7, __pyx_t_4) : __Pyx_PyObject_CallOneArg(__pyx_t_6, __pyx_t_4);
+  __Pyx_XDECREF(__pyx_t_7); __pyx_t_7 = 0;
+  __Pyx_DECREF(__pyx_t_4); __pyx_t_4 = 0;
+  if (unlikely(!__pyx_t_5)) __PYX_ERR(0, 13, __pyx_L1_error)
+  __Pyx_GOTREF(__pyx_t_5);
+  __Pyx_DECREF(__pyx_t_6); __pyx_t_6 = 0;
+  if (__Pyx_SetNameInClass(__pyx_t_3, __pyx_n_s_value, __pyx_t_5) < 0) __PYX_ERR(0, 14, __pyx_L1_error)
+  __Pyx_DECREF(__pyx_t_5); __pyx_t_5 = 0;
+
   /* "nyoibo/entities/entity.pyx":4
  *
  *
  * class Entity(metaclass=MetaEntity):             # <<<<<<<<<<<<<<
  *
- *     def __init__(self, value):
+ *     def __init__(self, value=None):
  */
   __pyx_t_5 = __Pyx_Py3ClassCreate(__pyx_t_1, __pyx_n_s_Entity, __pyx_empty_tuple, __pyx_t_3, __pyx_t_2, 1, 0); if (unlikely(!__pyx_t_5)) __PYX_ERR(0, 4, __pyx_L1_error)
   __Pyx_GOTREF(__pyx_t_5);
@@ -1910,6 +2098,8 @@ if (!__Pyx_RefNanny) {
   __Pyx_XDECREF(__pyx_t_3);
   __Pyx_XDECREF(__pyx_t_4);
   __Pyx_XDECREF(__pyx_t_5);
+  __Pyx_XDECREF(__pyx_t_6);
+  __Pyx_XDECREF(__pyx_t_7);
   if (__pyx_m) {
     if (__pyx_d) {
       __Pyx_AddTraceback("init nyoibo.entities.entity", __pyx_clineno, __pyx_lineno, __pyx_filename);
@@ -1975,32 +2165,6 @@ static PyObject *__Pyx_GetBuiltinName(PyObject *name) {
     return result;
 }
 
-/* RaiseArgTupleInvalid */
-static void __Pyx_RaiseArgtupleInvalid(
-    const char* func_name,
-    int exact,
-    Py_ssize_t num_min,
-    Py_ssize_t num_max,
-    Py_ssize_t num_found)
-{
-    Py_ssize_t num_expected;
-    const char *more_or_less;
-    if (num_found < num_min) {
-        num_expected = num_min;
-        more_or_less = "at least";
-    } else {
-        num_expected = num_max;
-        more_or_less = "at most";
-    }
-    if (exact) {
-        more_or_less = "exactly";
-    }
-    PyErr_Format(PyExc_TypeError,
-                 "%.200s() takes %.8s %" CYTHON_FORMAT_SSIZE_T "d positional argument%.1s (%" CYTHON_FORMAT_SSIZE_T "d given)",
-                 func_name, more_or_less, num_expected,
-                 (num_expected == 1) ? "" : "s", num_found);
-}
-
 /* RaiseDoubleKeywords */
 static void __Pyx_RaiseDoubleKeywordsError(
     const char* func_name,
@@ -2117,6 +2281,32 @@ static int __Pyx_ParseOptionalKeywords(
     return -1;
 }
 
+/* RaiseArgTupleInvalid */
+static void __Pyx_RaiseArgtupleInvalid(
+    const char* func_name,
+    int exact,
+    Py_ssize_t num_min,
+    Py_ssize_t num_max,
+    Py_ssize_t num_found)
+{
+    Py_ssize_t num_expected;
+    const char *more_or_less;
+    if (num_found < num_min) {
+        num_expected = num_min;
+        more_or_less = "at least";
+    } else {
+        num_expected = num_max;
+        more_or_less = "at most";
+    }
+    if (exact) {
+        more_or_less = "exactly";
+    }
+    PyErr_Format(PyExc_TypeError,
+                 "%.200s() takes %.8s %" CYTHON_FORMAT_SSIZE_T "d positional argument%.1s (%" CYTHON_FORMAT_SSIZE_T "d given)",
+                 func_name, more_or_less, num_expected,
+                 (num_expected == 1) ? "" : "s", num_found);
+}
+
 /* PyObjectSetAttrStr */
 #if CYTHON_USE_TYPE_SLOTS
 static CYTHON_INLINE int __Pyx_PyObject_SetAttrStr(PyObject* obj, PyObject* attr_name, PyObject* value) {
@@ -3147,6 +3337,35 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_CallOneArg(PyObject *func, PyObjec
 }
 #endif
 
+/* PyObjectCall2Args */
+static CYTHON_UNUSED PyObject* __Pyx_PyObject_Call2Args(PyObject* function, PyObject* arg1, PyObject* arg2) {
+    PyObject *args, *result = NULL;
+    #if CYTHON_FAST_PYCALL
+    if (PyFunction_Check(function)) {
+        PyObject *args[2] = {arg1, arg2};
+        return __Pyx_PyFunction_FastCall(function, args, 2);
+    }
+    #endif
+    #if CYTHON_FAST_PYCCALL
+    if (__Pyx_PyFastCFunction_Check(function)) {
+        PyObject *args[2] = {arg1, arg2};
+        return __Pyx_PyCFunction_FastCall(function, args, 2);
+    }
+    #endif
+    args = PyTuple_New(2);
+    if (unlikely(!args)) goto done;
+    Py_INCREF(arg1);
+    PyTuple_SET_ITEM(args, 0, arg1);
+    Py_INCREF(arg2);
+    PyTuple_SET_ITEM(args, 1, arg2);
+    Py_INCREF(function);
+    result = __Pyx_PyObject_Call(function, args, NULL);
+    Py_DECREF(args);
+    Py_DECREF(function);
+done:
+    return result;
+}
+
 /* CalculateMetaclass */
 static PyObject *__Pyx_CalculateMetaclass(PyTypeObject *metaclass, PyObject *bases) {
     Py_ssize_t i, nbases = PyTuple_GET_SIZE(bases);
diff --git a/nyoibo/entities/entity.pyx b/nyoibo/entities/entity.pyx
index 3e8abd4..ad89c69 100644
--- a/nyoibo/entities/entity.pyx
+++ b/nyoibo/entities/entity.pyx
@@ -3,9 +3,13 @@ from .meta_entity import MetaEntity
 
 class Entity(metaclass=MetaEntity):
 
-    def __init__(self, value):
+    def __init__(self, value=None):
         self._value = value
 
     @property
     def value(self):
         return self._value
+
+    @value.setter
+    def value(self, value):
+        self._value = value
diff --git a/tests/test_entity.py b/tests/test_entity.py
index 2598789..42359e3 100644
--- a/tests/test_entity.py
+++ b/tests/test_entity.py
@@ -4,11 +4,11 @@
 from nyoibo.exceptions import PrivateField
 
 
-def test_entity():
+class Rate(Entity):
+    _value = fields.StrField()
 
-    class Rate(Entity):
-        _value = fields.StrField()
 
+def test_entity():
     rate = Rate(value='0.25')
 
     assert rate.value == '0.25'
@@ -18,3 +18,10 @@ def test_fields_must_be_private():
     with raises(PrivateField):
         class Example(Entity):
             value = fields.StrField()
+
+
+def test_set_value():
+    rate = Rate()
+    rate.value = '0.25'
+
+    assert rate.value == '0.25'