diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..cb50efe
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,24 @@
+name: Python package
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.8]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip tox
+      - name: Build and test
+        run: |
+          tox
diff --git a/.pylintrc b/.pylintrc
index 33809a1..1a26ad7 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -1,5 +1,5 @@
 [MESSAGES CONTROL]
-disable=invalid-name, missing-docstring, locally-disabled, unbalanced-tuple-unpacking,no-else-return,fixme,duplicate-code,cyclic-import,import-outside-toplevel
+disable=invalid-name, missing-docstring, locally-disabled, unbalanced-tuple-unpacking,no-else-return,fixme,duplicate-code,cyclic-import,import-outside-toplevel,consider-using-with
 
 [SIMILARITIES]
 min-similarity-lines=5
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 3f8b32d..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-sudo: false
-language: python
-python:
-  - "3.6"
-  - "3.7"
-  - "3.8"
-  - "3.9"
-
-cache:
-  directories:
-    - $HOME/.cache/pip
-
-before_install:
-  - pip install -U pip wheel
-  - pip install -U setuptools
-  - pip install -U pylint coverage pycodestyle pydocstyle
-
-install:
-  - pip install -U -e .
-
-script:
-  - pycodestyle libagent
-  - pylint --reports=no --rcfile .pylintrc libagent
-  - pydocstyle libagent
-  - coverage run --source libagent/ -m py.test -v
-
-after_success:
-  - coverage report
-
diff --git a/README.md b/README.md
index aea311f..8af2b7e 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,5 @@
 # Hardware-based SSH/GPG agent
 
-[![Build Status](https://travis-ci.org/romanz/trezor-agent.svg?branch=master)](https://travis-ci.org/romanz/trezor-agent)
 [![Chat](https://badges.gitter.im/romanz/trezor-agent.svg)](https://gitter.im/romanz/trezor-agent)
 
 This project allows you to use various hardware security devices to operate GPG and SSH.  Instead of keeping your key on your computer and decrypting it with a passphrase when you want to use it, the key is generated and stored on the device and never reaches your computer.  Read more about the design [here](doc/DESIGN.md).
diff --git a/libagent/device/fake_device.py b/libagent/device/fake_device.py
index 37710d1..8edeecd 100644
--- a/libagent/device/fake_device.py
+++ b/libagent/device/fake_device.py
@@ -5,8 +5,8 @@ import logging
 
 import ecdsa
 
-from . import interface
 from .. import formats
+from . import interface
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/device/keepkey.py b/libagent/device/keepkey.py
index 3a086e5..a8d265b 100644
--- a/libagent/device/keepkey.py
+++ b/libagent/device/keepkey.py
@@ -1,7 +1,7 @@
 """KeepKey-related code (see https://www.keepkey.com/)."""
 
-from . import trezor
 from .. import formats
+from . import trezor
 
 
 def _verify_support(identity, ecdh):
diff --git a/libagent/device/keepkey_defs.py b/libagent/device/keepkey_defs.py
index d95c66a..8514961 100644
--- a/libagent/device/keepkey_defs.py
+++ b/libagent/device/keepkey_defs.py
@@ -2,8 +2,9 @@
 
 # pylint: disable=unused-import,import-error
 
-from keepkeylib.client import CallException, PinException
+from keepkeylib.client import CallException
 from keepkeylib.client import KeepKeyClient as Client
+from keepkeylib.client import PinException
 from keepkeylib.messages_pb2 import PassphraseAck, PinMatrixAck
 from keepkeylib.transport_hid import HidTransport
 from keepkeylib.transport_webusb import WebUsbTransport
diff --git a/libagent/device/ledger.py b/libagent/device/ledger.py
index 2edfe79..039feac 100644
--- a/libagent/device/ledger.py
+++ b/libagent/device/ledger.py
@@ -6,8 +6,8 @@ import struct
 
 from ledgerblue import comm  # pylint: disable=import-error
 
-from . import interface
 from .. import formats
+from . import interface
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/device/onlykey.py b/libagent/device/onlykey.py
index addfb62..5594963 100644
--- a/libagent/device/onlykey.py
+++ b/libagent/device/onlykey.py
@@ -2,10 +2,11 @@
 # pylint: disable=attribute-defined-outside-init
 """OnlyKey-related code (see https://www.onlykey.io/)."""
 
-import logging
-import hashlib
 import codecs
+import hashlib
+import logging
 import time
+
 import ecdsa
 import nacl.signing
 import unidecode
diff --git a/libagent/device/onlykey_defs.py b/libagent/device/onlykey_defs.py
index 04d6df4..c716a0f 100644
--- a/libagent/device/onlykey_defs.py
+++ b/libagent/device/onlykey_defs.py
@@ -2,4 +2,4 @@
 
 # pylint: disable=unused-import,import-error,no-name-in-module
 
-from onlykey import OnlyKey, Message
+from onlykey import Message, OnlyKey
diff --git a/libagent/device/trezor.py b/libagent/device/trezor.py
index 81104f3..8fdbd11 100644
--- a/libagent/device/trezor.py
+++ b/libagent/device/trezor.py
@@ -5,8 +5,8 @@ import logging
 
 import semver
 
-from . import interface
 from .. import formats
+from . import interface
 
 log = logging.getLogger(__name__)
 
@@ -71,6 +71,7 @@ class Trezor(interface.Device):
                 log.exception('ping failed: %s', e)
                 connection.close()  # so the next HID open() will succeed
                 raise
+        return None
 
     def close(self):
         """Close connection."""
diff --git a/libagent/device/trezor_defs.py b/libagent/device/trezor_defs.py
index 916c869..8080bf4 100644
--- a/libagent/device/trezor_defs.py
+++ b/libagent/device/trezor_defs.py
@@ -1,20 +1,20 @@
 """TREZOR-related definitions."""
 
+import logging
 # pylint: disable=unused-import,import-error,no-name-in-module,no-member
 import os
-import logging
 
 import mnemonic
 import semver
+
 import trezorlib
-
-from trezorlib.client import TrezorClient as Client, PASSPHRASE_TEST_PATH
-from trezorlib.exceptions import TrezorFailure, PinException
-from trezorlib.transport import get_transport
-from trezorlib.messages import IdentityType
-
 from trezorlib.btc import get_address, get_public_node
-from trezorlib.misc import sign_identity, get_ecdh_session_key
+from trezorlib.client import PASSPHRASE_TEST_PATH
+from trezorlib.client import TrezorClient as Client
+from trezorlib.exceptions import PinException, TrezorFailure
+from trezorlib.messages import IdentityType
+from trezorlib.misc import get_ecdh_session_key, sign_identity
+from trezorlib.transport import get_transport
 
 log = logging.getLogger(__name__)
 
@@ -28,3 +28,4 @@ def find_device():
         return get_transport(os.environ.get("TREZOR_PATH"))
     except Exception as e:  # pylint: disable=broad-except
         log.debug("Failed to find a Trezor device: %s", e)
+        return None
diff --git a/libagent/device/ui.py b/libagent/device/ui.py
index 4d91437..0048626 100644
--- a/libagent/device/ui.py
+++ b/libagent/device/ui.py
@@ -5,12 +5,13 @@ import os
 import subprocess
 import sys
 
+from .. import util
+
 try:
     from trezorlib.client import PASSPHRASE_ON_DEVICE
 except ImportError:
     PASSPHRASE_ON_DEVICE = object()
 
-from .. import util
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/gpg/__init__.py b/libagent/gpg/__init__.py
index 3711bc8..edb7cda 100644
--- a/libagent/gpg/__init__.py
+++ b/libagent/gpg/__init__.py
@@ -21,9 +21,8 @@ import time
 import pkg_resources
 import semver
 
-
-from . import agent, client, encode, keyring, protocol
 from .. import device, formats, server, util
+from . import agent, client, encode, keyring, protocol
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/gpg/agent.py b/libagent/gpg/agent.py
index d7b3837..a4cb99c 100644
--- a/libagent/gpg/agent.py
+++ b/libagent/gpg/agent.py
@@ -2,8 +2,8 @@
 import binascii
 import logging
 
-from . import client, decode, keyring, protocol
 from .. import util
+from . import client, decode, keyring, protocol
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/gpg/decode.py b/libagent/gpg/decode.py
index 470369e..8694dff 100644
--- a/libagent/gpg/decode.py
+++ b/libagent/gpg/decode.py
@@ -9,8 +9,8 @@ import struct
 import ecdsa
 import nacl.signing
 
-from . import protocol
 from .. import util
+from . import protocol
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/gpg/encode.py b/libagent/gpg/encode.py
index a334fd4..0eac71f 100644
--- a/libagent/gpg/encode.py
+++ b/libagent/gpg/encode.py
@@ -2,8 +2,8 @@
 import io
 import logging
 
-from . import decode, keyring, protocol
 from .. import util
+from . import decode, keyring, protocol
 
 log = logging.getLogger(__name__)
 
diff --git a/libagent/gpg/protocol.py b/libagent/gpg/protocol.py
index c0bb7eb..f722b51 100644
--- a/libagent/gpg/protocol.py
+++ b/libagent/gpg/protocol.py
@@ -4,6 +4,7 @@ import base64
 import hashlib
 import logging
 import struct
+
 import nacl.signing
 
 from .. import formats, util
diff --git a/libagent/gpg/tests/test_decode.py b/libagent/gpg/tests/test_decode.py
index c5a0604..5398e42 100644
--- a/libagent/gpg/tests/test_decode.py
+++ b/libagent/gpg/tests/test_decode.py
@@ -4,8 +4,8 @@ import os
 
 import pytest
 
-from .. import decode, protocol
 from ... import util
+from .. import decode, protocol
 
 
 def test_subpackets():
diff --git a/libagent/gpg/tests/test_protocol.py b/libagent/gpg/tests/test_protocol.py
index cc9be43..233be13 100644
--- a/libagent/gpg/tests/test_protocol.py
+++ b/libagent/gpg/tests/test_protocol.py
@@ -2,8 +2,8 @@ import ecdsa
 import nacl.signing
 import pytest
 
-from .. import protocol
 from ... import formats
+from .. import protocol
 
 
 def test_packet():
diff --git a/libagent/signify/__init__.py b/libagent/signify/__init__.py
index faf4d3a..f7ad7ab 100644
--- a/libagent/signify/__init__.py
+++ b/libagent/signify/__init__.py
@@ -16,7 +16,6 @@ import time
 import pkg_resources
 import semver
 
-
 from .. import formats, server, util
 from ..device import interface, ui
 
diff --git a/libagent/ssh/__init__.py b/libagent/ssh/__init__.py
index 10cc029..614404d 100644
--- a/libagent/ssh/__init__.py
+++ b/libagent/ssh/__init__.py
@@ -11,9 +11,9 @@ import sys
 import tempfile
 import threading
 
-import pkg_resources
 import configargparse
 import daemon
+import pkg_resources
 
 from .. import device, formats, server, util
 from . import client, protocol
diff --git a/tox.ini b/tox.ini
index acbe911..3d6cc1a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@ deps=
     isort<5
 commands=
     pycodestyle libagent
-    # isort --skip-glob .tox -c -r libagent
+    isort --skip-glob .tox -c -rc libagent
     pylint --reports=no --rcfile .pylintrc libagent
     pydocstyle libagent
     coverage run --source libagent -m py.test -v libagent