diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..f4952ba
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,8 @@
+version: 2
+updates:
+- package-ecosystem: pip
+  directory: "/"
+  schedule:
+    interval: daily
+    time: "10:00"
+  open-pull-requests-limit: 10
diff --git a/.pylintrc b/.pylintrc
index ccf3cb6..1db55e1 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -10,8 +10,6 @@ ignore=conf.py
 init-hook="from pylint.config import find_pylintrc; import os, sys; sys.path.append(os.path.dirname(find_pylintrc()))"
 
 [pre-commit-hook]
-# C0122: Misplaced comparison constant (tests use Yoda conditions).
-# C0330: Wrong hanging indentation (conflicts with `black`).
 # W0621: Redefining name from outer scope (conflicts with pytest fixtures).
-disable=C0122,C0330,W0621
-limit=10.0
+disable=W0621
+limit=10
diff --git a/.travis.yml b/.travis.yml
index 4f83f82..2d73e11 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,6 @@ python:
   - "3.8"
   - "3.7"
   - "3.6"
-  - "3.5"
   # Disabled until typed_ast (used by pylint) is fixed.
   # See https://github.com/python/typed_ast/issues/134
   # - "pypy3"
diff --git a/countdoom/cli.py b/countdoom/cli.py
index c2e03da..a390f0d 100644
--- a/countdoom/cli.py
+++ b/countdoom/cli.py
@@ -105,7 +105,7 @@ def check_positive(value) -> int:
         int_value = int(value)
         if int_value <= 0:
             raise argparse.ArgumentTypeError(
-                "{} is an invalid positive integer value".format(value)
+                f"{value} is an invalid positive integer value"
             )
         return int_value
 
@@ -127,7 +127,7 @@ def check_positive(value) -> int:
         '--v',
         '--version',
         action='version',
-        version='%(prog)s {version}'.format(version=countdoom.__version__),
+        version=f'%(prog)s {countdoom.__version__}',
     )
     parser.add_argument(
         '-h',
diff --git a/countdoom/client.py b/countdoom/client.py
index 9baf7f1..35060bc 100644
--- a/countdoom/client.py
+++ b/countdoom/client.py
@@ -160,17 +160,21 @@ async def _fetch(self, url: str, timeout: int = None) -> str:
             raise CountdoomClientError("Session not started.")
 
         try:
-            async with async_timeout.timeout(timeout):
-                async with self._session.get(url, timeout=timeout) as resp:
-                    if resp.status != 200:
-                        raise AssertionError
-                    return await resp.text()
-        except AssertionError:
+            async with (
+                async_timeout.timeout(timeout),
+                self._session.get(url, timeout=timeout) as resp
+            ):
+                if resp.status != 200:
+                    raise AssertionError
+                return await resp.text()
+        except AssertionError as exc:
             await self.close()
-            raise CountdoomClientError("Page not found.")
-        except OSError:
+            raise CountdoomClientError("Page not found.") from exc
+        except OSError as exc:
             await self.close()
-            raise CountdoomClientError("Cannot connect to website. Check URL.")
+            raise CountdoomClientError(
+                "Cannot connect to website. Check URL."
+            ) from exc
 
     async def _extract_sentence(self) -> None:
         """
@@ -187,20 +191,20 @@ async def _extract_sentence(self) -> None:
             self._sentence = re.sub(r'\s+', ' ', sentence).strip()
             if not self._sentence:
                 raise ValueError()
-        except IndexError:
+        except IndexError as exc:
             _LOGGER.error(
                 "No sentence found using selector %s. Check for source "
                 "website design changes.",
                 self.SELECTOR,
             )
-            raise CountdoomClientError("No sentence found.")
-        except ValueError:
+            raise CountdoomClientError("No sentence found.") from exc
+        except ValueError as exc:
             _LOGGER.error(
                 "Empty sentence found using selector %s. Check for source "
                 "website design changes.",
                 self.SELECTOR,
             )
-            raise CountdoomClientError("Empty sentence found.")
+            raise CountdoomClientError("Empty sentence found.") from exc
         _LOGGER.debug("Sentence found: %s", self._sentence)
 
     async def close(self) -> None:
@@ -223,11 +227,11 @@ def _sentence_to_countdown(self) -> None:
 
         try:
             self._countdown = self.sentence_to_countdown(self._sentence)
-        except AttributeError:
+        except AttributeError as exc:
             _LOGGER.error(
                 "Regex pattern yielded no result for : %s", self._sentence
             )
-            raise CountdoomClientError("Sentence not parsable.")
+            raise CountdoomClientError("Sentence not parsable.") from exc
         _LOGGER.debug("Countdown value: %s", self._countdown)
 
     @classmethod
diff --git a/setup.cfg b/setup.cfg
index fc7ad27..1bb3986 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,7 +30,8 @@ ignore_missing_imports = true
 # Configure pytest
 # See https://docs.pytest.org/
 [tool:pytest]
-collect_ignore = ['setup.py']
-addopts = --strict
+addopts =
+    --ignore=setup.py,
+    --strict-markers
 markers =
     live
diff --git a/setup.py b/setup.py
index 2ae4a47..8d2b2d3 100644
--- a/setup.py
+++ b/setup.py
@@ -15,10 +15,10 @@
 from setuptools import find_packages, setup
 
 # Load documentation for PyPI.
-with open('README.rst') as readme_file:
+with open('README.rst', encoding="utf-8") as readme_file:
     README = readme_file.read()
 
-with open('CHANGELOG.rst') as history_file:
+with open('CHANGELOG.rst', encoding="utf-8") as history_file:
     HISTORY = history_file.read()
 
 # Define extra requirements for different installation environments.
@@ -88,9 +88,9 @@
 
 # Define URLs.
 DOCS_URL = 'https://countdoom.readthedocs.io/'
-HISTORY_URL = '{}en/latest/changelog.html'.format(DOCS_URL)
+HISTORY_URL = f'{DOCS_URL}en/latest/changelog.html'
 REPO_URL = 'https://github.com/renemarc/countdoom'
-ISSUES_URL = '{}/issues'.format(REPO_URL)
+ISSUES_URL = f'{REPO_URL}/issues'
 
 setup(
     author='René-Marc Simard',
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 8c8dfe3..d603725 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -23,7 +23,7 @@ def _setup_mock_server(mocked: aioresponses) -> None:
 
     :param mocked: aiohttp response
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
     string = "IT IS 1 MINUTE TO MIDNIGHT"
     mocked.get(
@@ -119,7 +119,7 @@ async def test_cli_request_version(capsys: CaptureFixture) -> None:
 
     assert exception.type == SystemExit
     assert exception.value.code == 0
-    assert "countdoom {}".format(countdoom.__version__) in output[0]
+    assert f"countdoom {countdoom.__version__}" in output[0]
 
 
 @pytest.mark.asyncio
@@ -271,7 +271,7 @@ async def test_cli_request_internal_error(capsys: CaptureFixture) -> None:
     :param capsys: System-level capture fixture
     """
     with aioresponses() as mocked:
-        prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+        prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
         suffix = '</h3>'
         string = ' '
         mocked.get(
diff --git a/tests/test_client.py b/tests/test_client.py
index 0085d9e..bdb325d 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -122,7 +122,7 @@ def response() -> Response:
 
     :return: Request response
     """
-    return requests.get(CountdoomClient.CLOCK_URL)
+    return requests.get(CountdoomClient.CLOCK_URL, timeout=5)
 
 
 def _get_path(string: str) -> str:
@@ -142,16 +142,13 @@ def _setup_servers(httpserver: HTTPServer) -> None:
 
     :param httpserver: HTTP Server
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
 
     sentences = SENTENCES_VALID + SENTENCES_INVALID
-    # sentences = SENTENCES_VALID
-    # for sentence in SENTENCES_INVALID:
-    #     sentences.append(sentence)
     for sentence in sentences:
         path = _get_path(sentence[0])
-        httpserver.expect_request('/{}'.format(path)).respond_with_data(
+        httpserver.expect_request(f'/{path}').respond_with_data(
             prefix + sentence[0] + suffix
         )
 
@@ -197,7 +194,7 @@ async def test_valid_sentence(httpserver: HTTPServer, sentence: str) -> None:
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -223,7 +220,7 @@ async def test_valid_countdown(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -249,7 +246,7 @@ async def test_valid_minutes(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -275,7 +272,7 @@ async def test_valid_clock(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -302,7 +299,7 @@ async def test_valid_time(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -329,7 +326,7 @@ async def test_invalid_minutes(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     with pytest.raises(CountdoomClientError) as err:
         await client.fetch_data()
@@ -356,7 +353,7 @@ async def test_invalid_clock(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     with pytest.raises(CountdoomClientError) as err:
         await client.fetch_data()
@@ -383,7 +380,7 @@ async def test_invalid_time(
 
     client = CountdoomClient()
     path = _get_path(sentence)
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     with pytest.raises(CountdoomClientError) as err:
         await client.fetch_data()
@@ -399,16 +396,16 @@ async def test_invalid_selector(httpserver: HTTPServer) -> None:
 
     :param httpserver: HTTP Server
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
     string = "IT IS 1 AND A HALF MINUTE TO MIDNIGHT"
     path = 'test_invalid_selector'
-    httpserver.expect_request('/{}'.format(path)).respond_with_data(
+    httpserver.expect_request(f'/{path}').respond_with_data(
         prefix + string + suffix
     )
 
     client = CountdoomClient()
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     selector = '.wrong-id-' + str(random.randint(0, 100000000))
     setattr(client, 'CLOCK_URL', clock_url)
     setattr(client, 'SELECTOR', selector)
@@ -425,16 +422,16 @@ async def test_htmlized_sentence(httpserver: HTTPServer) -> None:
 
     :param httpserver: HTTP Server
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
     string = " IT  IS <em>STILL</em> 1 <b>MINUTE</b> TO  MIDNIGHT"
     path = 'test_htmlized_sentence'
-    httpserver.expect_request('/{}'.format(path)).respond_with_data(
+    httpserver.expect_request(f'/{path}').respond_with_data(
         prefix + string + suffix
     )
 
     client = CountdoomClient()
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -450,16 +447,16 @@ async def test_empty_sentence(httpserver: HTTPServer) -> None:
 
     :param httpserver: HTTP Server
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
     string = ' '
     path = 'test_empty_sentence'
-    httpserver.expect_request('/{}'.format(path)).respond_with_data(
+    httpserver.expect_request(f'/{path}').respond_with_data(
         prefix + string + suffix
     )
 
     client = CountdoomClient()
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     with pytest.raises(CountdoomClientError) as err:
         await client.fetch_data()
@@ -500,16 +497,16 @@ async def test_formatted_time(httpserver: HTTPServer) -> None:
 
     :param httpserver: HTTP Server
     """
-    prefix = '<h3 class="{}">'.format(CountdoomClient.SELECTOR[1:])
+    prefix = f'<h3 class="{CountdoomClient.SELECTOR[1:]}">'
     suffix = '</h3>'
     string = "IT IS 16 MINUTES TO MIDNIGHT"
     path = 'test_formatted_time'
-    httpserver.expect_request('/{}'.format(path)).respond_with_data(
+    httpserver.expect_request(f'/{path}').respond_with_data(
         prefix + string + suffix
     )
 
     client = CountdoomClient()
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     data = await client.fetch_data()
 
@@ -526,7 +523,7 @@ async def test_url_not_found(httpserver: HTTPServer) -> None:
     """
     path = 'test_url_not_found'
     client = CountdoomClient()
-    clock_url = httpserver.url_for('/{}'.format(path))
+    clock_url = httpserver.url_for(f'/{path}')
     setattr(client, 'CLOCK_URL', clock_url)
     with pytest.raises(CountdoomClientError) as err:
         await client.fetch_data()
diff --git a/tests/test_package.py b/tests/test_package.py
index 468428c..8356388 100644
--- a/tests/test_package.py
+++ b/tests/test_package.py
@@ -19,11 +19,11 @@ def test_package_main() -> None:
     This check uses a subprocess to validate the package, since the
     package's __main__.py cannot be imported for tests.
     """
-    process = subprocess.Popen(
+    with subprocess.Popen(
         ['python', '-m', 'countdoom', '--version'],
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
-    )
-    stdout = process.communicate()[0]
+    ) as process:
+        stdout = process.communicate()[0]
 
-    assert 'countdoom {}'.format(countdoom.__version__) in str(stdout)
+    assert f'countdoom {countdoom.__version__}' in str(stdout)
diff --git a/tox.ini b/tox.ini
index ff18480..a4d76a1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,7 @@
 # See https://tox.readthedocs.io/
 
 [tox]
-envlist = lint, py3{5,6,7,8}, pypy3
+envlist = lint, py3{6,7,8}, pypy3
 skip_missing_interpreters = true
 
 [travis]
@@ -14,7 +14,6 @@ python =
     3.8: py38
     3.7: py37
     3.6: py36
-    3.5: py35
 
 [testenv]
 setenv =