diff --git a/README.md b/README.md
index ee3dd83..2975c3a 100644
--- a/README.md
+++ b/README.md
@@ -21,29 +21,30 @@ In this example we start with a simple atomic class expression and move to some
 ones and finally render and print the last of them in description logics syntax.
 
 ```python
-from owlapy.model import IRI, OWLClass, OWLObjectProperty, OWLObjectSomeValuesFrom, \
-                         OWLObjectIntersectionOf
+from owlapy.iri import IRI
+from owlapy.owl_class_expression import OWLClass, OWLObjectIntersectionOf
+from owlapy.owl_property import OWLObjectProperty
+from owlapy.owl_restriction import OWLObjectSomeValuesFrom
+
 from owlapy.owl2sparql.converter import owl_expression_to_sparql
 from owlapy.render import owl_expression_to_dl
 
-# Create an IRI object using the iri as a string for 'male' class.
-male_iri = IRI.create('http://example.com/society#male')
 
 # Create the male class
-male = OWLClass(male_iri)
+male = OWLClass("http://example.com/society#male")
 
 # Create an object property using the iri as a string for 'hasChild' property.
-hasChild = OWLObjectProperty(IRI.create('http://example.com/society#hasChild'))
+hasChild = OWLObjectProperty("http://example.com/society#hasChild")
 
 # Create an existential restrictions
 males_with_children = OWLObjectSomeValuesFrom(hasChild, male)
 
 # Let's make it more complex by intersecting with another class
-teacher = OWLClass(IRI.create('http://example.com/society#teacher'))
+teacher = OWLClass("http://example.com/society#teacher")
 male_teachers_with_children = OWLObjectIntersectionOf([males_with_children, teacher])
 
 # You can render and print owl class expressions in description logics syntax (and vice-versa)
-print(owl_expression_to_dl(male_teachers_with_children)) 
+print(owl_expression_to_dl(male_teachers_with_children))
 # (∃ hasChild.male) ⊓ teacher
 print(owl_expression_to_sparql("?x", male_teachers_with_children))
 #  SELECT DISTINCT ?x WHERE {  ?x <http://example.com/society#hasChild> ?s_1 . ?s_1 a <http://example.com/society#male> . ?x a <http://example.com/society#teacher> .  } }
diff --git a/owlapy/owl_class_expression.py b/owlapy/owl_class_expression.py
index a971cee..edb1a96 100644
--- a/owlapy/owl_class_expression.py
+++ b/owlapy/owl_class_expression.py
@@ -6,7 +6,7 @@
 from .owl_literal import OWLLiteral
 from typing import Final, Sequence, Union, Iterable
 from .owl_property import OWLDataPropertyExpression, OWLObjectProperty, OWLDataProperty
-
+from .iri import IRI
 from owlapy.vocab import OWLRDFVocabulary, XSDVocabulary
 
 
@@ -123,15 +123,19 @@ class OWLClass(OWLClassExpression, OWLEntity):
     _is_nothing: bool
     _is_thing: bool
 
-    def __init__(self, iri: 'IRI'):
+    def __init__(self, iri: Union[IRI,str]):
         """Gets an instance of OWLClass that has the specified IRI.
 
         Args:
-            iri: The IRI.
+            iri:
         """
-        self._is_nothing = iri.is_nothing()
-        self._is_thing = iri.is_thing()
-        self._iri = iri
+        if isinstance(iri, IRI):
+            self._iri = iri
+        else:
+            self._iri = IRI.create(iri)
+
+        self._is_nothing = self._iri.is_nothing()
+        self._is_thing = self._iri.is_thing()
 
     def get_iri(self) -> 'IRI':
         # documented in parent