diff --git a/chirptext/__version__.py b/chirptext/__version__.py
index <HASH>..<HASH> 100644
--- a/chirptext/__version__.py
+++ b/chirptext/__version__.py
@@ -10,6 +10,6 @@ __description__ = "ChirpText is a collection of text processing tools for Python
 __url__ = "https://letuananh.github.io/chirptext/"
 __maintainer__ = "Le Tuan Anh"
 __version_major__ = "0.1"
-__version__ = "{}a20".format(__version_major__)
+__version__ = "{}a21".format(__version_major__)
 __version_long__ = "{} - Alpha".format(__version_major__)
 __status__ = "Prototype"
pump version to <I>a<I>