diff --git a/.github/workflows/zeyple.yml b/.github/workflows/zeyple.yml
index 8f65669..263933b 100644
--- a/.github/workflows/zeyple.yml
+++ b/.github/workflows/zeyple.yml
@@ -28,16 +28,18 @@ jobs:
           sudo apt-get install debconf-utils
           sudo debconf-set-selections <<< "postfix postfix/main_mailer_type string 'Local only'"
           sudo debconf-set-selections <<< "postfix postfix/mailname string localhost"
-          sudo apt-get install -y mailutils ruby ruby-dev rubygems build-essential sudo gnupg python3-gpg
+          sudo apt-get install -y mailutils ruby ruby-dev rubygems build-essential sudo gnupg python3-gpg libgpgme11 libgpgme-dev
           sudo gem install --no-document fpm
           python -m pip install --upgrade pip setuptools wheel
-          python -m pip install --upgrade tox
+          python -m pip install --upgrade mock pycodestyle pytest pytest-cov
       - name: Build deb package
         run: ./fpm/create
       - name: End to end test using deb package
         run:  sudo bash -ex ./tests/e2e.sh
-      - name: Test with tox
-        run: tox
+      - name: Lint with pycodestyle
+        run: pycodestyle --show-pep8 --max-line-length=100
+      - name: Test with pytest
+        run: env PYTHONPATH=$PYTHONPATH:/usr/lib/python3/dist-packages python -m pytest --cov=zeyple/ --cov-report=html
       - name: Upload deb package
         uses: actions/upload-artifact@v1
         with:
diff --git a/tests/test_zeyple.py b/tests/test_zeyple.py
index a724d41..817c81e 100644
--- a/tests/test_zeyple.py
+++ b/tests/test_zeyple.py
@@ -1,9 +1,12 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from __future__ import absolute_import
+
 from configparser import ConfigParser
 from textwrap import dedent
 from unittest.mock import Mock
+from gpg import _gpgme
 import gpg
 import os
 import re
@@ -14,6 +17,8 @@
 
 from zeyple import zeyple as z
 
+del absolute_import
+
 KEYS_FNAME = os.path.join(os.path.dirname(__file__), 'keys.gpg')
 TEST1_ID = 'D6513C04E24C1F83'
 TEST1_EMAIL = 'test1@zeyple.example.com'
diff --git a/zeyple/zeyple.py b/zeyple/zeyple.py
index 8b14b3c..8f4a28b 100755
--- a/zeyple/zeyple.py
+++ b/zeyple/zeyple.py
@@ -1,6 +1,8 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from __future__ import absolute_import
+
 from configparser import ConfigParser
 from io import BytesIO
 import copy
@@ -15,13 +17,7 @@
 import smtplib
 import sys
 
-
-def message_from_binary(message):
-    return email.message_from_bytes(message)
-
-
-def as_binary_string(email):
-    return email.as_bytes()
+del absolute_import
 
 
 def encode_string(string):
@@ -84,7 +80,7 @@ def process_message(self, message_data, recipients):
         """Encrypts the message with recipient keys"""
         message_data = encode_string(message_data)
 
-        in_message = message_from_binary(message_data)
+        in_message = email.message_from_bytes(message_data)
         logging.info(
             "Processing outgoing message %s", in_message['Message-id'])
 
@@ -190,7 +186,7 @@ def _encrypt_message(self, in_message, key_id):
             # remove superfluous header
             del mixed['MIME-Version']
 
-            payload = as_binary_string(mixed)
+            payload = mixed.as_bytes()
 
         encrypted_payload = self._encrypt_payload(payload, [key_id])