diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 5ba1d63..6c19858 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -41,7 +41,7 @@ jobs:
       if: ${{ contains(matrix.deps, 'pycurl') }}
       run: sudo apt install -y libcurl4-openssl-dev
     - name: Install Python deps
-      run: pip install -U ${{ matrix.deps }} pytest pytest-asyncio pytest-httpbin flaky structlog toml appdirs
+      run: pip install -U ${{ matrix.deps }} pytest pytest-asyncio pytest-httpbin flaky structlog toml appdirs lxml
     - name: Decrypt keys
       env:
         KEY: ${{ secrets.KEY }}
diff --git a/docs/usage.rst b/docs/usage.rst
index 417f3ba..3ea61a6 100644
--- a/docs/usage.rst
+++ b/docs/usage.rst
@@ -286,7 +286,7 @@ xpath
   An xpath expression used to find the version string.
 
 .. note:: 
-  An additional dependency "lxml" is required
+  An additional dependency "lxml" is required.
 
 Find with a Command
 ~~~~~~~~~~~~~~~~~~~
diff --git a/mypy.ini b/mypy.ini
index a02b84b..1aead6f 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -20,3 +20,6 @@ ignore_missing_imports = True
 
 [mypy-appdirs]
 ignore_missing_imports = True
+
+[mypy-lxml]
+ignore_missing_imports = True
diff --git a/nvchecker/api.py b/nvchecker/api.py
index e03a076..cd9b991 100644
--- a/nvchecker/api.py
+++ b/nvchecker/api.py
@@ -8,4 +8,4 @@ from .util import (
 )
 from .sortversion import sort_version_keys
 
-from .ctxvars import tries, proxy, user_agent, httptoken, entry_waiter
\ No newline at end of file
+from .ctxvars import tries, proxy, user_agent, httptoken, entry_waiter
diff --git a/nvchecker/ctxvars.py b/nvchecker/ctxvars.py
index b827850..eb82a29 100644
--- a/nvchecker/ctxvars.py
+++ b/nvchecker/ctxvars.py
@@ -17,4 +17,4 @@ tries = ContextVar('tries', default=1)
 proxy: ContextVar[Optional[str]] = ContextVar('proxy', default=None)
 user_agent = ContextVar('user_agent', default=DEFAULT_USER_AGENT)
 httptoken = ContextVar('httptoken', default=None)
-entry_waiter: ContextVar[EntryWaiter] = ContextVar('entry_waiter')
\ No newline at end of file
+entry_waiter: ContextVar[EntryWaiter] = ContextVar('entry_waiter')
diff --git a/nvchecker/util.py b/nvchecker/util.py
index 0d6bb5d..42994e2 100644
--- a/nvchecker/util.py
+++ b/nvchecker/util.py
@@ -264,7 +264,6 @@ class FunctionWorker(BaseWorker):
     except Exception as e:
       await self.result_q.put(RawResult(name, e, entry))
 
-
 class GetVersionError(Exception):
   '''An error occurred while getting version information.
 
diff --git a/tests/test_htmlpasrer.py b/tests/test_htmlpasrer.py
index dcbabae..f3be52b 100644
--- a/tests/test_htmlpasrer.py
+++ b/tests/test_htmlpasrer.py
@@ -18,4 +18,4 @@ async def test_xpath_missing_ok(get_version):
         "url": "http://httpbin.org/",
         "xpath": '//pre[@class="test-is-ok"]/text()',
         "missing_ok": True,
-    }) is None
\ No newline at end of file
+    }) is None
diff --git a/tests/test_httpheader.py b/tests/test_httpheader.py
index 53ddd3a..091dbc2 100644
--- a/tests/test_httpheader.py
+++ b/tests/test_httpheader.py
@@ -3,7 +3,7 @@
 
 import pytest
 import pytest_httpbin
-assert pytest_httpbin  # for pyflakes
+assert pytest_httpbin # for pyflakes
 pytestmark = [pytest.mark.asyncio, pytest.mark.needs_net]
 
 async def test_redirection(get_version):
@@ -11,7 +11,7 @@ async def test_redirection(get_version):
         "source": "httpheader",
         "url": "https://www.unifiedremote.com/download/linux-x64-deb",
         "regex": r'urserver-([\d.]+).deb',
-    }) != None
+    }) is not None
 
 async def test_get_version_withtoken(get_version, httpbin):
     assert await get_version("unifiedremote", {
@@ -20,4 +20,4 @@ async def test_get_version_withtoken(get_version, httpbin):
         "httptoken": "Basic dXNlcm5hbWU6c3VwZXJwYXNzd29yZA==",
         "header": "server",
         "regex": r'([0-9.]+)*',
-    }) != None
\ No newline at end of file
+    }) is not None
diff --git a/tests/test_regex.py b/tests/test_regex.py
index 65f4102..739700c 100644
--- a/tests/test_regex.py
+++ b/tests/test_regex.py
@@ -5,7 +5,7 @@ import base64
 
 import pytest
 import pytest_httpbin
-assert pytest_httpbin  # for pyflakes
+assert pytest_httpbin # for pyflakes
 
 pytestmark = pytest.mark.asyncio
 
@@ -57,4 +57,4 @@ async def test_regex_with_tokenBearer(get_version, httpbin):
         "url": httpbin.url + "/bearer",
         "httptoken": "Bearer username:password",
         "regex": r'"token":"([a-w]+):.*"',
-    }) == "username"
\ No newline at end of file
+    }) == "username"