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/libagent/device/trezor.py b/libagent/device/trezor.py
index 81104f3..3cb1345 100644
--- a/libagent/device/trezor.py
+++ b/libagent/device/trezor.py
@@ -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..79107f6 100644
--- a/libagent/device/trezor_defs.py
+++ b/libagent/device/trezor_defs.py
@@ -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/tox.ini b/tox.ini
index acbe911..b6c377b 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