diff --git a/CherryTomato/__init__.py b/CherryTomato/__init__.py
index d1cb619..a70234f 100644
--- a/CherryTomato/__init__.py
+++ b/CherryTomato/__init__.py
@@ -4,6 +4,6 @@
 MEDIA_DIR = os.path.join(BASE_DIR, 'media')
 APP_ICON = os.path.join(MEDIA_DIR, 'icon.png')
 
-VERSION = '0.4.0'
+VERSION = '0.4.1'
 ORGANIZATION_NAME = 'yakimka'
 APPLICATION_NAME = 'CherryTomato'
diff --git a/CherryTomato/__main__.py b/CherryTomato/__main__.py
deleted file mode 100644
index 12a7e52..0000000
--- a/CherryTomato/__main__.py
+++ /dev/null
@@ -1 +0,0 @@
-from . import main
diff --git a/CherryTomato/about_window.py b/CherryTomato/about_window.py
index 2b16915..0946ca5 100644
--- a/CherryTomato/about_window.py
+++ b/CherryTomato/about_window.py
@@ -3,7 +3,7 @@
 from PyQt5.QtGui import QIcon
 
 from CherryTomato import APP_ICON, VERSION
-from .about_ui import Ui_About
+from CherryTomato.about_ui import Ui_About
 
 
 class About(QtWidgets.QWidget, Ui_About):
diff --git a/CherryTomato/main.py b/CherryTomato/main.py
index 5755c38..6ee5a2c 100755
--- a/CherryTomato/main.py
+++ b/CherryTomato/main.py
@@ -8,12 +8,18 @@
 from CherryTomato import ORGANIZATION_NAME, APPLICATION_NAME
 from CherryTomato.main_window import CherryTomatoMainWindow
 
-QCoreApplication.setOrganizationName(ORGANIZATION_NAME)
-QCoreApplication.setApplicationName(APPLICATION_NAME)
 
-app = Qt.QApplication(sys.argv)
+def main():
+    QCoreApplication.setOrganizationName(ORGANIZATION_NAME)
+    QCoreApplication.setApplicationName(APPLICATION_NAME)
 
-watch = CherryTomatoMainWindow()
-watch.show()
+    app = Qt.QApplication(sys.argv)
 
-app.exec_()
+    watch = CherryTomatoMainWindow()
+    watch.show()
+
+    app.exec_()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/CherryTomato/settings.py b/CherryTomato/settings.py
index d05ea44..623e2f7 100644
--- a/CherryTomato/settings.py
+++ b/CherryTomato/settings.py
@@ -105,7 +105,9 @@ def autoStopBreak(self, val):
 
     @property
     def switchToTomatoOnAbort(self):
-        return self.settings.value(self.SWITCH_TO_TOMATO_ON_ABORT, self.SWITCH_TO_TOMATO_ON_ABORT_DEFAULT, type=bool)
+        return self.settings.value(
+            self.SWITCH_TO_TOMATO_ON_ABORT, self.SWITCH_TO_TOMATO_ON_ABORT_DEFAULT, type=bool
+        )
 
     @switchToTomatoOnAbort.setter
     def switchToTomatoOnAbort(self, val):
@@ -133,7 +135,9 @@ def stateBreak(self, min):
 
     @property
     def stateLongBreak(self):
-        return self.settings.value(self.STATE_LONG_BREAK, State('long_break', self.LONG_BREAK_DEFAULT))
+        return self.settings.value(
+            self.STATE_LONG_BREAK, State('long_break', self.LONG_BREAK_DEFAULT)
+        )
 
     @stateLongBreak.setter
     def stateLongBreak(self, min):
diff --git a/CherryTomato/tomato_timer.py b/CherryTomato/tomato_timer.py
index 69dca4d..58dd7c1 100644
--- a/CherryTomato/tomato_timer.py
+++ b/CherryTomato/tomato_timer.py
@@ -89,7 +89,9 @@ def changeState(self):
     def _statesGen(self):
         while True:
             yield self.settings.stateTomato
-            yield self.settings.stateLongBreak if self._isTimeForLongBreak() else self.settings.stateBreak
+            longBreak = self.settings.stateLongBreak
+            break_ = self.settings.stateBreak
+            yield longBreak if self._isTimeForLongBreak() else break_
 
     def _isTimeForLongBreak(self):
         if self.tomatoes == 0:
diff --git a/CherryTomato/widget.py b/CherryTomato/widget.py
index 814a480..60801ca 100644
--- a/CherryTomato/widget.py
+++ b/CherryTomato/widget.py
@@ -90,12 +90,9 @@ def calculateInnerRect(self, outerRadius: float):
         secondInnerRect = QRectF(left, top + firstHeight, width, height - firstHeight)
         return firstInnerRect, secondInnerRect, innerRadius
 
-    def drawTwoTexts(self,
-                     p: QPainter,
-                     firstRect: QRectF,
-                     secondRect: QRectF,
-                     innerRadius: float,
-                     value: float):
+    def drawTwoTexts(
+        self, p: QPainter, firstRect: QRectF, secondRect: QRectF, innerRadius: float, value: float
+    ):
         if not self.m_format:
             return
         f = QFont(self.font())
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f313b71
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,30 @@
+all: init clean lint test
+
+clean: clean-build clean-pyc  ## Clean build files and pyc files
+	rm -fr htmlcov/
+
+clean-build:  ## Clean build files
+	rm -fr build/
+	rm -fr dist/
+	rm -fr *.egg-info
+
+clean-pyc:  ## Clean pyc files
+	find . -name '*.pyc' -exec rm -f {} +
+	find . -name '*.pyo' -exec rm -f {} +
+	find . -name '*~' -exec rm -f {} +
+
+init:  ## Install test packages
+	pip install pytest pytest-qt pytest-mock flake8
+
+test:  ## Run tests
+	pytest
+
+flake:  ## Run flake8
+	flake8 --statistics --count
+
+lint: flake  ## Run all linters
+
+.PHONY: help
+
+help:
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
diff --git a/requirements.txt b/requirements.txt
deleted file mode 100644
index 876effd..0000000
--- a/requirements.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-PyQt5
-qroundprogressbar
-pytest
-pytest-qt
-pytest-mock
diff --git a/setup.py b/setup.py
index f6b6c38..4599fd1 100644
--- a/setup.py
+++ b/setup.py
@@ -1,14 +1,16 @@
 from setuptools import setup
 
-setup(name='CherryTomato',
-      author='yakimka',
-      version='0.4.0',
-      packages=['CherryTomato'],
-      python_requires='>=3.6',
-      install_requires=['PyQt5', 'qroundprogressbar'],
-      url='https://github.com/yakimka/CherryTomato',
-      license='GPL',
-      entry_points={'gui_scripts': ['cherry_tomato = CherryTomato.main']},
-      package_data={
-            '': ['media/*.*'],
-      })
+from CherryTomato import VERSION
+
+setup(
+    name='CherryTomato',
+    author='yakimka',
+    version=VERSION,
+    packages=['CherryTomato'],
+    python_requires='>=3.6',
+    install_requires=['PyQt5', 'qroundprogressbar'],
+    url='https://github.com/yakimka/CherryTomato',
+    license='GPL',
+    entry_points={'gui_scripts': ['cherry_tomato = CherryTomato.main:main']},
+    package_data={'': ['media/*.*'], },
+)
diff --git a/tests/conftest.py b/tests/conftest.py
index 0fd40c0..83dc0a3 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -16,8 +16,6 @@ def value(self, key, default, type=None):
 
 @pytest.fixture
 def mock_qsettings(monkeypatch, mocker):
-    qsettings = mocker.patch('CherryTomato.settings.QSettings', MockQSettings)
-
     monkeypatch.setattr(CherryTomatoSettings, 'TOMATO_DEFAULT', 100)
     monkeypatch.setattr(CherryTomatoSettings, 'BREAK_DEFAULT', 25)
     monkeypatch.setattr(CherryTomatoSettings, 'LONG_BREAK_DEFAULT', 50)
@@ -26,13 +24,12 @@ def mock_qsettings(monkeypatch, mocker):
     monkeypatch.setattr(CherryTomatoSettings, 'AUTO_STOP_BREAK_DEFAULT', False)
     monkeypatch.setattr(CherryTomatoSettings, 'SWITCH_TO_TOMATO_ON_ABORT_DEFAULT', True)
 
-    return qsettings
+    return mocker.patch('CherryTomato.settings.QSettings', MockQSettings)
+
 
 @pytest.fixture
 def settings(mock_qsettings):
-    settings = CherryTomatoSettings()
-
-    return settings
+    return CherryTomatoSettings()
 
 
 @pytest.fixture
diff --git a/tests/ui/test_main_window.py b/tests/ui/test_main_window.py
index f9c7a69..7b15344 100644
--- a/tests/ui/test_main_window.py
+++ b/tests/ui/test_main_window.py
@@ -27,4 +27,3 @@ def test_stop_button_with_tomato(mock_main_window, qtbot):
     qtbot.mouseClick(mock_main_window.button, QtCore.Qt.LeftButton)
 
     assert mock_main_window.tomatoTimer.running is False
-
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..feb881c
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,4 @@
+[flake8]
+max-complexity = 10
+max-line-length = 100
+exclude = *_ui.py,