diff --git a/setup.py b/setup.py
index 35330ff..c97e0be 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="nnf",
-    version='0.3.0',
+    version='0.4.0',
     author="Jan Verbeek, Christian Muise",
     author_email="jan.verbeek@posteo.nl, christian.muise@queensu.ca",
     description="Manipulate NNF (Negation Normal Form) logical sentences",