diff --git a/CHANGELOG b/CHANGELOG
index dbd314f..ea9f43a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,11 @@
 v0.3.1
+------
+
+What's new!
+'''''''''''
 
 - Simplified plot_3d function
+- Replace fortran code with numba jit python version.
 
 v0.3.0
 ------
@@ -8,7 +13,7 @@ v0.3.0
 What's new!
 '''''''''''
 
-- Added T1, T2 relaxation inversion kerenel.
+- Added T1, T2 relaxation inversion kernel.
 
 v0.2.0
 ------
diff --git a/mrinversion/__init__.py b/mrinversion/__init__.py
index 975b4e2..260c070 100644
--- a/mrinversion/__init__.py
+++ b/mrinversion/__init__.py
@@ -1 +1 @@
-__version__ = "0.3.1.dev1"
+__version__ = "0.3.1"
diff --git a/mrinversion/kernel/__init__.py b/mrinversion/kernel/__init__.py
index 73568c4..d6c5c68 100644
--- a/mrinversion/kernel/__init__.py
+++ b/mrinversion/kernel/__init__.py
@@ -1,2 +1,3 @@
+"""Initialization of the kernel module."""
 from mrinversion.kernel.relaxation import T1  # NOQA
 from mrinversion.kernel.relaxation import T2  # NOQA
diff --git a/mrinversion/kernel/base.py b/mrinversion/kernel/base.py
index 33a8ebb..681d95c 100644
--- a/mrinversion/kernel/base.py
+++ b/mrinversion/kernel/base.py
@@ -1,3 +1,4 @@
+"""Base classes for kernel generation."""
 from copy import deepcopy
 
 import csdmpy as cp
diff --git a/mrinversion/tests/fista_intergration_test.py b/mrinversion/tests/fista_intergration_test.py
index 3e67354..03dbe5d 100644
--- a/mrinversion/tests/fista_intergration_test.py
+++ b/mrinversion/tests/fista_intergration_test.py
@@ -1,3 +1,4 @@
+"""Integration tests for FISTA implementation."""
 import csdmpy as cp
 import numpy as np
 
diff --git a/setup.cfg b/setup.cfg
index 0e2a323..0fbf5f6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -16,3 +16,4 @@ addopts =
 omit =
     setup.py
     mrinversion/utils.py
+    mrinversion/linear_model/fista/__init__.py
diff --git a/setup.py b/setup.py
index 859826a..c4432a3 100644
--- a/setup.py
+++ b/setup.py
@@ -1,10 +1,11 @@
+"""Setup for mrinversion package."""
 from os.path import abspath
 from os.path import dirname
 from os.path import join
 from setuptools import find_packages, setup
 
 
-with open("mrinversion/__init__.py") as f:
+with open("mrinversion/__init__.py", encoding="utf-8") as f:
     for line in f.readlines():
         if "__version__" in line:
             before_keyword, keyword, after_keyword = line.partition("=")
@@ -32,7 +33,7 @@
         "Python based statistical learning of NMR tensor and relaxation parameters "
         "distribution."
     ),
-    long_description=open(join(module_dir, "README.md")).read(),
+    long_description=open(join(module_dir, "README.md"), encoding="utf-8").read(),
     long_description_content_type="text/markdown",
     author="Deepansh J. Srivastava",
     author_email="deepansh2012@gmail.com",