diff --git a/CHANGES.rst b/CHANGES.rst
index 95b6cfd..437ebd0 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,11 @@
 Changelog
 =========
 
+1.2.0 (2019-01-15)
+------------------
+
+- Reduced the creation time
+
 1.1.1 (2015-09-05)
 ------------------
 
diff --git a/README.rst b/README.rst
index 0098917..f5b7fec 100644
--- a/README.rst
+++ b/README.rst
@@ -187,7 +187,7 @@ Test
     > PYTHONPATH=$PYTHONPATH:. mamba
 
 
-.. |Version Number| image:: https://img.shields.io/badge/version-1.1.1-blue.svg
+.. |Version Number| image:: https://img.shields.io/badge/version-1.2.0-blue.svg
 
 .. |Build Status| image:: https://travis-ci.org/quiqueporta/simple-value-object.svg?branch=master
     :target: https://travis-ci.org/quiqueporta/simple-value-object
diff --git a/simple_value_object/__init__.py b/simple_value_object/__init__.py
index be9a167..5012e2d 100644
--- a/simple_value_object/__init__.py
+++ b/simple_value_object/__init__.py
@@ -3,7 +3,7 @@
 from .value_object import ValueObject
 from .decorators import invariant
 
-VERSION = (1, 1, 1, 'final')
+VERSION = (1, 2, 0, 'final')
 __version__ = VERSION
 
 
diff --git a/simple_value_object/value_object.py b/simple_value_object/value_object.py
index 2fba4b7..a2e669a 100644
--- a/simple_value_object/value_object.py
+++ b/simple_value_object/value_object.py
@@ -53,22 +53,23 @@ def check_invariants():
                     )
 
         def invariant_execute(invariant):
-            return_value = getattr(self, invariant)(self)
+            return_value = invariant(self, self)
 
             if not isinstance(return_value, bool):
                 raise InvariantReturnValueException()
 
             return return_value
 
+        def is_invariant(method):
+            try:
+                return 'invariant_func_wrapper' in str(method) and '__init__' not in str(method)
+            except TypeError:
+                return False
+
         def obtain_invariants():
-            for member in inspect.getmembers(cls):
-                try:
-                    is_method = hasattr(member[1], '__call__')
-                    is_a_invariant_method = 'invariant_func_wrapper' in inspect.getsourcelines(member[1].__code__)[0][0]
-                    if is_method and is_a_invariant_method:
-                        yield(member[0])
-                except AttributeError:
-                    continue
+            invariants = [member[1] for member in inspect.getmembers(cls, is_invariant)]
+            for invariant in invariants:
+                yield(invariant)
 
         def check_mutable_data_types():
             mutable_types = (list, dict, set)