diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 21a0985..8f0b7cd 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -14,6 +14,10 @@ repos:
     hooks:
       - id: flake8
         additional_dependencies: [flake8-import-order, flake8-bugbear]
+  - repo: https://github.com/asottile/reorder_python_imports
+    rev: v2.3.0
+    hooks:
+    -   id: reorder-python-imports
   - repo: local
     hooks:
       - id: update-travis
diff --git a/.travis.yml b/.travis.yml
index 59a2f35..c104147 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,74 +19,22 @@
     "include": [
       {
         "env": "BUILD=style",
-        "python": "3.6"
+        "python": "3.7"
       },
       {
         "env": "BUILD=test REQUIREMENTS=release",
-        "python": "3.5"
-      },
-      {
-        "dist": "trusty",
-        "env": "BUILD=test-storage DAV_SERVER=radicale REQUIREMENTS=release ",
-        "python": "3.5"
-      },
-      {
-        "dist": "trusty",
-        "env": "BUILD=test-storage DAV_SERVER=xandikos REQUIREMENTS=release ",
-        "python": "3.5"
-      },
-      {
-        "env": "BUILD=test REQUIREMENTS=minimal",
-        "python": "3.5"
-      },
-      {
-        "dist": "trusty",
-        "env": "BUILD=test-storage DAV_SERVER=radicale REQUIREMENTS=minimal ",
-        "python": "3.5"
-      },
-      {
-        "dist": "trusty",
-        "env": "BUILD=test-storage DAV_SERVER=xandikos REQUIREMENTS=minimal ",
-        "python": "3.5"
-      },
-      {
-        "env": "BUILD=test REQUIREMENTS=release",
-        "python": "3.6"
+        "python": "3.7"
       },
       {
         "env": "BUILD=test-storage DAV_SERVER=radicale REQUIREMENTS=release ",
-        "python": "3.6"
+        "python": "3.7"
       },
       {
         "env": "BUILD=test-storage DAV_SERVER=xandikos REQUIREMENTS=release ",
-        "python": "3.6"
+        "python": "3.7"
       },
       {
         "env": "BUILD=test-storage DAV_SERVER=fastmail REQUIREMENTS=release ",
-        "python": "3.6"
-      },
-      {
-        "env": "BUILD=test REQUIREMENTS=minimal",
-        "python": "3.6"
-      },
-      {
-        "env": "BUILD=test-storage DAV_SERVER=radicale REQUIREMENTS=minimal ",
-        "python": "3.6"
-      },
-      {
-        "env": "BUILD=test-storage DAV_SERVER=xandikos REQUIREMENTS=minimal ",
-        "python": "3.6"
-      },
-      {
-        "env": "BUILD=test REQUIREMENTS=release",
-        "python": "3.7"
-      },
-      {
-        "env": "BUILD=test-storage DAV_SERVER=radicale REQUIREMENTS=release ",
-        "python": "3.7"
-      },
-      {
-        "env": "BUILD=test-storage DAV_SERVER=xandikos REQUIREMENTS=release ",
         "python": "3.7"
       },
       {
@@ -127,7 +75,7 @@
       },
       {
         "env": "BUILD=test ETESYNC_TESTS=true REQUIREMENTS=latest",
-        "python": "3.6"
+        "python": "3.7"
       }
     ]
   },
diff --git a/Makefile b/Makefile
index 805caf0..fbe59b8 100644
--- a/Makefile
+++ b/Makefile
@@ -30,11 +30,6 @@ PYTEST_ARGS =
 
 TEST_EXTRA_PACKAGES =
 
-ifeq ($(COVERAGE), true)
-	TEST_EXTRA_PACKAGES += pytest-cov
-	PYTEST_ARGS += --cov-config .coveragerc --cov vdirsyncer
-endif
-
 ifeq ($(ETESYNC_TESTS), true)
 	TEST_EXTRA_PACKAGES += git+https://github.com/etesync/journal-manager@v0.5.2
 	TEST_EXTRA_PACKAGES += django djangorestframework==3.8.2 wsgi_intercept drf-nested-routers
@@ -106,9 +101,6 @@ docs:
 linkcheck:
 	sphinx-build -W -b linkcheck ./docs/ ./docs/_build/linkcheck/
 
-release:
-	python setup.py sdist bdist_wheel upload
-
 release-deb:
 	sh scripts/release-deb.sh debian jessie
 	sh scripts/release-deb.sh debian stretch
diff --git a/docs/conf.py b/docs/conf.py
index 385d2e8..5fe5e51 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -65,7 +65,7 @@ def github_issue_role(name, rawtext, text, lineno, inliner,
         if issue_num <= 0:
             raise ValueError()
     except ValueError:
-        msg = inliner.reporter.error('Invalid GitHub issue: {}'.format(text),
+        msg = inliner.reporter.error(f'Invalid GitHub issue: {text}',
                                      line=lineno)
         prb = inliner.problematic(rawtext, rawtext, msg)
         return [prb], [msg]
diff --git a/docs/installation.rst b/docs/installation.rst
index 7690f2d..2d33c57 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -41,7 +41,7 @@ If your distribution doesn't provide a package for vdirsyncer, you still can
 use Python's package manager "pip". First, you'll have to check that the
 following things are installed:
 
-- Python 3.5+ and pip.
+- Python 3.7+ and pip.
 - ``libxml`` and ``libxslt``
 - ``zlib``
 - Linux or OS X. **Windows is not supported**, see :gh:`535`.
diff --git a/scripts/make_travisconf.py b/scripts/make_travisconf.py
index 8a2d630..7c790e5 100755
--- a/scripts/make_travisconf.py
+++ b/scripts/make_travisconf.py
@@ -1,10 +1,8 @@
 #!/usr/bin/env python
-
 import itertools
 import json
 
-python_versions = ("3.5", "3.6", "3.7", "3.8")
-latest_python = "3.6"
+python_versions = ["3.7", "3.8"]
 
 cfg = {}
 
@@ -34,7 +32,7 @@ matrix = []
 cfg['matrix'] = {'include': matrix, 'fast_finish': True}
 
 matrix.append({
-    'python': latest_python,
+    'python': python_versions[0],
     'env': 'BUILD=style'
 })
 
@@ -51,7 +49,7 @@ for python, requirements in itertools.product(
         'env': f"BUILD=test REQUIREMENTS={requirements}",
     })
 
-    if python == latest_python and requirements == "release":
+    if python == python_versions[0] and requirements == "release":
         dav_servers += ("fastmail",)
 
     for dav_server in dav_servers:
@@ -61,8 +59,6 @@ for python, requirements in itertools.product(
                     f"DAV_SERVER={dav_server} "
                     f"REQUIREMENTS={requirements} ")
         }
-        if python == '3.5':
-            job['dist'] = 'trusty'
 
         if dav_server in ("davical", "icloud"):
             job['if'] = 'NOT (type IN (pull_request))'
@@ -70,7 +66,7 @@ for python, requirements in itertools.product(
         matrix.append(job)
 
 matrix.append({
-    'python': latest_python,
+    'python': python_versions[0],
     'env': ("BUILD=test "
             "ETESYNC_TESTS=true "
             "REQUIREMENTS=latest")
diff --git a/setup.cfg b/setup.cfg
index fb86724..e3d4d5c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -3,7 +3,12 @@ universal = 1
 
 [tool:pytest]
 norecursedirs = tests/storage/servers/*
-addopts = --tb=short
+addopts =
+  --tb=short
+  --cov-config .coveragerc
+  --cov=vdirsyncer
+  --cov-report=term-missing
+  --no-cov-on-fail
 
 [flake8]
 # E731: Use a def instead of lambda expr
diff --git a/setup.py b/setup.py
index 653be04..d584b95 100644
--- a/setup.py
+++ b/setup.py
@@ -4,14 +4,14 @@ Vdirsyncer synchronizes calendars and contacts.
 Please refer to https://vdirsyncer.pimutils.org/en/stable/packaging.html for
 how to package vdirsyncer.
 '''
-
-
-from setuptools import Command, find_packages, setup
+from setuptools import Command
+from setuptools import find_packages
+from setuptools import setup
 
 
 requirements = [
     # https://github.com/mitsuhiko/click/issues/200
-    'click>=5.0,<6.0',
+    'click>=5.0',
     'click-log>=0.3.0, <0.4.0',
 
     # https://github.com/pimutils/vdirsyncer/issues/478
@@ -87,8 +87,6 @@ setup(
         'License :: OSI Approved :: BSD License',
         'Operating System :: POSIX',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Topic :: Internet',
diff --git a/test-requirements.txt b/test-requirements.txt
index feb39a6..b6e1181 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,4 +1,5 @@
 hypothesis>=5.0.0
 pytest
+pytest-cov
 pytest-localserver
 pytest-subtesthack
diff --git a/tests/__init__.py b/tests/__init__.py
index 6948552..71f69b4 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,14 +1,11 @@
 '''
 Test suite for vdirsyncer.
 '''
-
 import hypothesis.strategies as st
+import urllib3.exceptions
 
 from vdirsyncer.vobject import normalize_item
 
-import urllib3
-import urllib3.exceptions
-
 urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
 
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 5ed34f9..b05da73 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -5,10 +5,10 @@ import logging
 import os
 
 import click_log
-
-from hypothesis import HealthCheck, Verbosity, settings
-
 import pytest
+from hypothesis import HealthCheck
+from hypothesis import settings
+from hypothesis import Verbosity
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/storage/__init__.py b/tests/storage/__init__.py
index dd0d0b3..a2e0022 100644
--- a/tests/storage/__init__.py
+++ b/tests/storage/__init__.py
@@ -1,25 +1,27 @@
 import random
-import uuid
-
 import textwrap
-from urllib.parse import quote as urlquote, unquote as urlunquote
+import uuid
+from urllib.parse import quote as urlquote
+from urllib.parse import unquote as urlunquote
 
 import hypothesis.strategies as st
+import pytest
 from hypothesis import given
 
-import pytest
-
+from .. import assert_item_equals
+from .. import EVENT_TEMPLATE
+from .. import normalize_item
+from .. import printable_characters_strategy
+from .. import TASK_TEMPLATE
+from .. import VCARD_TEMPLATE
 from vdirsyncer import exceptions
 from vdirsyncer.storage.base import normalize_meta_value
 from vdirsyncer.vobject import Item
 
-from .. import EVENT_TEMPLATE, TASK_TEMPLATE, VCARD_TEMPLATE, \
-    assert_item_equals, normalize_item, printable_characters_strategy
-
 
 def get_server_mixin(server_name):
     from . import __name__ as base
-    x = __import__('{}.servers.{}'.format(base, server_name), fromlist=[''])
+    x = __import__(f'{base}.servers.{server_name}', fromlist=[''])
     return x.ServerMixin
 
 
@@ -183,7 +185,7 @@ class StorageTests:
     def test_discover(self, requires_collections, get_storage_args, get_item):
         collections = set()
         for i in range(1, 5):
-            collection = 'test{}'.format(i)
+            collection = f'test{i}'
             s = self.storage_class(**get_storage_args(collection=collection))
             assert not list(s.list())
             s.upload(get_item())
diff --git a/tests/storage/conftest.py b/tests/storage/conftest.py
index dcb42f6..96865a6 100644
--- a/tests/storage/conftest.py
+++ b/tests/storage/conftest.py
@@ -1,7 +1,7 @@
-import pytest
-
 import uuid
 
+import pytest
+
 
 @pytest.fixture
 def slow_create_collection(request):
diff --git a/tests/storage/dav/__init__.py b/tests/storage/dav/__init__.py
index 8886f73..3003df6 100644
--- a/tests/storage/dav/__init__.py
+++ b/tests/storage/dav/__init__.py
@@ -1,19 +1,15 @@
+import os
 import uuid
 
-import os
-
 import pytest
-
-import requests
 import requests.exceptions
 
+from .. import get_server_mixin
+from .. import StorageTests
 from tests import assert_item_equals
-
 from vdirsyncer import exceptions
 from vdirsyncer.vobject import Item
 
-from .. import StorageTests, get_server_mixin
-
 
 dav_server = os.environ.get('DAV_SERVER', 'skip')
 ServerMixin = get_server_mixin(dav_server)
diff --git a/tests/storage/dav/test_caldav.py b/tests/storage/dav/test_caldav.py
index b999e25..e1f996e 100644
--- a/tests/storage/dav/test_caldav.py
+++ b/tests/storage/dav/test_caldav.py
@@ -2,18 +2,17 @@ import datetime
 from textwrap import dedent
 
 import pytest
-
-import requests
 import requests.exceptions
 
-from tests import EVENT_TEMPLATE, TASK_TEMPLATE, VCARD_TEMPLATE
-
+from . import dav_server
+from . import DAVStorageTests
+from .. import format_item
+from tests import EVENT_TEMPLATE
+from tests import TASK_TEMPLATE
+from tests import VCARD_TEMPLATE
 from vdirsyncer import exceptions
 from vdirsyncer.storage.dav import CalDAVStorage
 
-from . import DAVStorageTests, dav_server
-from .. import format_item
-
 
 class TestCalDAVStorage(DAVStorageTests):
     storage_class = CalDAVStorage
diff --git a/tests/storage/dav/test_carddav.py b/tests/storage/dav/test_carddav.py
index e15e047..a371423 100644
--- a/tests/storage/dav/test_carddav.py
+++ b/tests/storage/dav/test_carddav.py
@@ -1,8 +1,7 @@
 import pytest
 
-from vdirsyncer.storage.dav import CardDAVStorage
-
 from . import DAVStorageTests
+from vdirsyncer.storage.dav import CardDAVStorage
 
 
 class TestCardDAVStorage(DAVStorageTests):
diff --git a/tests/storage/dav/test_main.py b/tests/storage/dav/test_main.py
index 5766b55..ef39c46 100644
--- a/tests/storage/dav/test_main.py
+++ b/tests/storage/dav/test_main.py
@@ -1,6 +1,8 @@
 import pytest
 
-from vdirsyncer.storage.dav import _BAD_XML_CHARS, _merge_xml, _parse_xml
+from vdirsyncer.storage.dav import _BAD_XML_CHARS
+from vdirsyncer.storage.dav import _merge_xml
+from vdirsyncer.storage.dav import _parse_xml
 
 
 def test_xml_utilities():
diff --git a/tests/storage/etesync/etesync_server/etesync_server/settings.py b/tests/storage/etesync/etesync_server/etesync_server/settings.py
index 4283f1b..eccdae9 100644
--- a/tests/storage/etesync/etesync_server/etesync_server/settings.py
+++ b/tests/storage/etesync/etesync_server/etesync_server/settings.py
@@ -9,7 +9,6 @@ https://docs.djangoproject.com/en/1.10/topics/settings/
 For the full list of settings and their values, see
 https://docs.djangoproject.com/en/1.10/ref/settings/
 """
-
 import os
 
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
diff --git a/tests/storage/etesync/etesync_server/etesync_server/urls.py b/tests/storage/etesync/etesync_server/etesync_server/urls.py
index 5b7fc61..921363d 100644
--- a/tests/storage/etesync/etesync_server/etesync_server/urls.py
+++ b/tests/storage/etesync/etesync_server/etesync_server/urls.py
@@ -13,11 +13,10 @@ Including another URLconf
     1. Import the include() function: from django.conf.urls import url, include
     2. Add a URL to urlpatterns:  url(r'^blog/', include('blog.urls'))
 """
-from django.conf.urls import include, url
-
-from rest_framework_nested import routers
-
+from django.conf.urls import include
+from django.conf.urls import url
 from journal import views
+from rest_framework_nested import routers
 
 router = routers.DefaultRouter()
 router.register(r'journals', views.JournalViewSet)
diff --git a/tests/storage/etesync/etesync_server/etesync_server/wsgi.py b/tests/storage/etesync/etesync_server/etesync_server/wsgi.py
index eeb40bc..147e71e 100644
--- a/tests/storage/etesync/etesync_server/etesync_server/wsgi.py
+++ b/tests/storage/etesync/etesync_server/etesync_server/wsgi.py
@@ -6,7 +6,6 @@ It exposes the WSGI callable as a module-level variable named ``application``.
 For more information on this file, see
 https://docs.djangoproject.com/en/1.10/howto/deployment/wsgi/
 """
-
 import os
 
 from django.core.wsgi import get_wsgi_application
diff --git a/tests/storage/etesync/test_main.py b/tests/storage/etesync/test_main.py
index 2045646..b258daa 100644
--- a/tests/storage/etesync/test_main.py
+++ b/tests/storage/etesync/test_main.py
@@ -1,14 +1,13 @@
-import shutil
 import os
+import shutil
 import sys
 
-
 import pytest
 import requests
 
-from vdirsyncer.storage.etesync import EtesyncContacts, EtesyncCalendars
-
 from .. import StorageTests
+from vdirsyncer.storage.etesync import EtesyncCalendars
+from vdirsyncer.storage.etesync import EtesyncContacts
 
 
 pytestmark = pytest.mark.skipif(os.getenv('ETESYNC_TESTS', '') != 'true',
diff --git a/tests/storage/servers/davical/__init__.py b/tests/storage/servers/davical/__init__.py
index a402ba2..550f6e9 100644
--- a/tests/storage/servers/davical/__init__.py
+++ b/tests/storage/servers/davical/__init__.py
@@ -1,7 +1,8 @@
 import os
-import pytest
 import uuid
 
+import pytest
+
 try:
     caldav_args = {
         # Those credentials are configured through the Travis UI
diff --git a/tests/storage/servers/mysteryshack/__init__.py b/tests/storage/servers/mysteryshack/__init__.py
index 617c154..b238bcc 100644
--- a/tests/storage/servers/mysteryshack/__init__.py
+++ b/tests/storage/servers/mysteryshack/__init__.py
@@ -1,10 +1,9 @@
 import os
+import shutil
 import subprocess
 import time
-import shutil
 
 import pytest
-
 import requests
 
 testserver_repo = os.path.dirname(__file__)
diff --git a/tests/storage/test_filesystem.py b/tests/storage/test_filesystem.py
index e8a3d71..c98e86a 100644
--- a/tests/storage/test_filesystem.py
+++ b/tests/storage/test_filesystem.py
@@ -2,11 +2,10 @@ import subprocess
 
 import pytest
 
+from . import StorageTests
 from vdirsyncer.storage.filesystem import FilesystemStorage
 from vdirsyncer.vobject import Item
 
-from . import StorageTests
-
 
 class TestFilesystemStorage(StorageTests):
     storage_class = FilesystemStorage
diff --git a/tests/storage/test_http.py b/tests/storage/test_http.py
index 5e63a8f..8c58c4e 100644
--- a/tests/storage/test_http.py
+++ b/tests/storage/test_http.py
@@ -1,11 +1,10 @@
 import pytest
-
 from requests import Response
 
 from tests import normalize_item
-
 from vdirsyncer.exceptions import UserError
-from vdirsyncer.storage.http import HttpStorage, prepare_auth
+from vdirsyncer.storage.http import HttpStorage
+from vdirsyncer.storage.http import prepare_auth
 
 
 def test_list(monkeypatch):
diff --git a/tests/storage/test_http_with_singlefile.py b/tests/storage/test_http_with_singlefile.py
index 6480a52..bb2b1bc 100644
--- a/tests/storage/test_http_with_singlefile.py
+++ b/tests/storage/test_http_with_singlefile.py
@@ -1,13 +1,11 @@
 import pytest
-
 from requests import Response
 
 import vdirsyncer.storage.http
+from . import StorageTests
 from vdirsyncer.storage.base import Storage
 from vdirsyncer.storage.singlefile import SingleFileStorage
 
-from . import StorageTests
-
 
 class CombinedStorage(Storage):
     '''A subclass of HttpStorage to make testing easier. It supports writes via
diff --git a/tests/storage/test_memory.py b/tests/storage/test_memory.py
index 417db1b..82db79c 100644
--- a/tests/storage/test_memory.py
+++ b/tests/storage/test_memory.py
@@ -1,8 +1,7 @@
 import pytest
 
-from vdirsyncer.storage.memory import MemoryStorage
-
 from . import StorageTests
+from vdirsyncer.storage.memory import MemoryStorage
 
 
 class TestMemoryStorage(StorageTests):
diff --git a/tests/storage/test_singlefile.py b/tests/storage/test_singlefile.py
index 54ef020..b645629 100644
--- a/tests/storage/test_singlefile.py
+++ b/tests/storage/test_singlefile.py
@@ -1,8 +1,7 @@
 import pytest
 
-from vdirsyncer.storage.singlefile import SingleFileStorage
-
 from . import StorageTests
+from vdirsyncer.storage.singlefile import SingleFileStorage
 
 
 class TestSingleFileStorage(StorageTests):
diff --git a/tests/system/cli/conftest.py b/tests/system/cli/conftest.py
index 43e4b79..fc2225e 100644
--- a/tests/system/cli/conftest.py
+++ b/tests/system/cli/conftest.py
@@ -1,8 +1,7 @@
 from textwrap import dedent
 
-from click.testing import CliRunner
-
 import pytest
+from click.testing import CliRunner
 
 import vdirsyncer.cli as cli
 
diff --git a/tests/system/cli/test_config.py b/tests/system/cli/test_config.py
index 734e1ee..b88dcd5 100644
--- a/tests/system/cli/test_config.py
+++ b/tests/system/cli/test_config.py
@@ -3,7 +3,8 @@ from textwrap import dedent
 
 import pytest
 
-from vdirsyncer import cli, exceptions
+from vdirsyncer import cli
+from vdirsyncer import exceptions
 from vdirsyncer.cli.config import Config
 
 
diff --git a/tests/system/cli/test_repair.py b/tests/system/cli/test_repair.py
index cad41f6..d3c05cf 100644
--- a/tests/system/cli/test_repair.py
+++ b/tests/system/cli/test_repair.py
@@ -19,7 +19,7 @@ def storage(tmpdir, runner):
 def test_basic(storage, runner, collection):
     if collection is not None:
         storage = storage.mkdir(collection)
-        collection_arg = 'foo/{}'.format(collection)
+        collection_arg = f'foo/{collection}'
     else:
         collection_arg = 'foo'
 
diff --git a/tests/system/cli/test_sync.py b/tests/system/cli/test_sync.py
index 97e21e8..43d35dd 100644
--- a/tests/system/cli/test_sync.py
+++ b/tests/system/cli/test_sync.py
@@ -3,9 +3,9 @@ import sys
 from textwrap import dedent
 
 import hypothesis.strategies as st
-from hypothesis import example, given
-
 import pytest
+from hypothesis import example
+from hypothesis import given
 
 
 def test_simple_run(tmpdir, runner):
@@ -123,7 +123,10 @@ def test_verbosity(tmpdir, runner):
     runner.write_with_general('')
     result = runner.invoke(['--verbosity=HAHA', 'sync'])
     assert result.exception
-    assert 'invalid value for "--verbosity"' in result.output.lower()
+    assert (
+        'invalid value for "--verbosity"' in result.output.lower()
+        or "invalid value for '--verbosity'" in result.output.lower()
+    )
 
 
 def test_collections_cache_invalidation(tmpdir, runner):
@@ -461,7 +464,7 @@ def test_partial_sync(tmpdir, runner, partial_sync):
     fileext = ".txt"
     path = "{base}/bar"
     '''.format(
-        partial_sync=('partial_sync = "{}"\n'.format(partial_sync)
+        partial_sync=(f'partial_sync = "{partial_sync}"\n'
                       if partial_sync else ''),
         base=str(tmpdir)
     )))
diff --git a/tests/system/cli/test_utils.py b/tests/system/cli/test_utils.py
index bbf8997..23aa997 100644
--- a/tests/system/cli/test_utils.py
+++ b/tests/system/cli/test_utils.py
@@ -1,6 +1,7 @@
 from vdirsyncer import exceptions
-from vdirsyncer.cli.utils import handle_cli_error, \
-    storage_instance_from_config, storage_names
+from vdirsyncer.cli.utils import handle_cli_error
+from vdirsyncer.cli.utils import storage_instance_from_config
+from vdirsyncer.cli.utils import storage_names
 
 
 def test_handle_cli_error(capsys):
diff --git a/tests/system/utils/test_main.py b/tests/system/utils/test_main.py
index 10bfde9..9df4e86 100644
--- a/tests/system/utils/test_main.py
+++ b/tests/system/utils/test_main.py
@@ -1,11 +1,12 @@
-import sys
 import logging
+import sys
 
 import click_log
 import pytest
 import requests
 
-from vdirsyncer import http, utils
+from vdirsyncer import http
+from vdirsyncer import utils
 
 
 @pytest.fixture(autouse=True)
diff --git a/tests/unit/cli/test_fetchparams.py b/tests/unit/cli/test_fetchparams.py
index 2d28507..664df5f 100644
--- a/tests/unit/cli/test_fetchparams.py
+++ b/tests/unit/cli/test_fetchparams.py
@@ -1,10 +1,10 @@
 import hypothesis.strategies as st
+import pytest
 from hypothesis import given
 
-import pytest
-
 from vdirsyncer import exceptions
-from vdirsyncer.cli.fetchparams import STRATEGIES, expand_fetch_params
+from vdirsyncer.cli.fetchparams import expand_fetch_params
+from vdirsyncer.cli.fetchparams import STRATEGIES
 
 
 @pytest.fixture
@@ -47,7 +47,7 @@ def test_key_conflict(monkeypatch, mystrategy):
 @given(s=st.text(), t=st.text(min_size=1))
 def test_fuzzing(s, t, mystrategy):
     config = expand_fetch_params({
-        '{}.fetch'.format(s): ['mystrategy', t]
+        f'{s}.fetch': ['mystrategy', t]
     })
 
     assert config[s] == t
diff --git a/tests/unit/sync/test_status.py b/tests/unit/sync/test_status.py
index b5fc912..6d7b549 100644
--- a/tests/unit/sync/test_status.py
+++ b/tests/unit/sync/test_status.py
@@ -1,7 +1,7 @@
-import pytest
-
-from hypothesis import assume, given
 import hypothesis.strategies as st
+import pytest
+from hypothesis import assume
+from hypothesis import given
 
 from vdirsyncer.sync.status import SqliteStatus
 
diff --git a/tests/unit/sync/test_sync.py b/tests/unit/sync/test_sync.py
index 4e9651f..1a2ac71 100644
--- a/tests/unit/sync/test_sync.py
+++ b/tests/unit/sync/test_sync.py
@@ -1,17 +1,22 @@
 from copy import deepcopy
 
 import hypothesis.strategies as st
-from hypothesis import assume
-from hypothesis.stateful import Bundle, RuleBasedStateMachine, rule
-
 import pytest
+from hypothesis import assume
+from hypothesis.stateful import Bundle
+from hypothesis.stateful import rule
+from hypothesis.stateful import RuleBasedStateMachine
 
-from tests import blow_up, uid_strategy
-
-from vdirsyncer.storage.memory import MemoryStorage, _random_string
+from tests import blow_up
+from tests import uid_strategy
+from vdirsyncer.storage.memory import _random_string
+from vdirsyncer.storage.memory import MemoryStorage
 from vdirsyncer.sync import sync as _sync
-from vdirsyncer.sync.exceptions import BothReadOnly, IdentConflict, \
-    PartialSync, StorageEmpty, SyncConflict
+from vdirsyncer.sync.exceptions import BothReadOnly
+from vdirsyncer.sync.exceptions import IdentConflict
+from vdirsyncer.sync.exceptions import PartialSync
+from vdirsyncer.sync.exceptions import StorageEmpty
+from vdirsyncer.sync.exceptions import SyncConflict
 from vdirsyncer.sync.status import SqliteStatus
 from vdirsyncer.vobject import Item
 
@@ -253,7 +258,7 @@ def test_conflict_resolution_both_etags_new(winning_storage):
     b.update(href_b, item_b, etag_b)
     with pytest.raises(SyncConflict):
         sync(a, b, status)
-    sync(a, b, status, conflict_resolution='{} wins'.format(winning_storage))
+    sync(a, b, status, conflict_resolution=f'{winning_storage} wins')
     assert items(a) == items(b) == {
         item_a.raw if winning_storage == 'a' else item_b.raw
     }
@@ -563,7 +568,7 @@ class SyncMachine(RuleBasedStateMachine):
           uid=uid_strategy,
           etag=st.text())
     def upload(self, storage, uid, etag):
-        item = Item('UID:{}'.format(uid))
+        item = Item(f'UID:{uid}')
         storage.items[uid] = (etag, item)
 
     @rule(storage=Storage, href=st.text())
diff --git a/tests/unit/test_metasync.py b/tests/unit/test_metasync.py
index ae6d94c..d342e70 100644
--- a/tests/unit/test_metasync.py
+++ b/tests/unit/test_metasync.py
@@ -1,12 +1,13 @@
 import hypothesis.strategies as st
-from hypothesis import example, given
-
 import pytest
+from hypothesis import example
+from hypothesis import given
 
 from tests import blow_up
-
 from vdirsyncer.exceptions import UserError
-from vdirsyncer.metasync import MetaSyncConflict, logger, metasync
+from vdirsyncer.metasync import logger
+from vdirsyncer.metasync import metasync
+from vdirsyncer.metasync import MetaSyncConflict
 from vdirsyncer.storage.base import normalize_meta_value
 from vdirsyncer.storage.memory import MemoryStorage
 
diff --git a/tests/unit/test_repair.py b/tests/unit/test_repair.py
index 5467c54..bac5ad5 100644
--- a/tests/unit/test_repair.py
+++ b/tests/unit/test_repair.py
@@ -1,10 +1,12 @@
-from hypothesis import HealthCheck, given, settings
-
 import pytest
+from hypothesis import given
+from hypothesis import HealthCheck
+from hypothesis import settings
 
 from tests import uid_strategy
-
-from vdirsyncer.repair import IrreparableItem, repair_item, repair_storage
+from vdirsyncer.repair import IrreparableItem
+from vdirsyncer.repair import repair_item
+from vdirsyncer.repair import repair_storage
 from vdirsyncer.storage.memory import MemoryStorage
 from vdirsyncer.utils import href_safe
 from vdirsyncer.vobject import Item
@@ -18,11 +20,11 @@ def test_repair_uids(uid):
     s.items = {
         'one': (
             'asdf',
-            Item('BEGIN:VCARD\nFN:Hans\nUID:{}\nEND:VCARD'.format(uid))
+            Item(f'BEGIN:VCARD\nFN:Hans\nUID:{uid}\nEND:VCARD')
         ),
         'two': (
             'asdf',
-            Item('BEGIN:VCARD\nFN:Peppi\nUID:{}\nEND:VCARD'.format(uid))
+            Item(f'BEGIN:VCARD\nFN:Peppi\nUID:{uid}\nEND:VCARD')
         )
     }
 
@@ -40,7 +42,7 @@ def test_repair_uids(uid):
 @settings(suppress_health_check=HealthCheck.all())
 def test_repair_unsafe_uids(uid):
     s = MemoryStorage()
-    item = Item('BEGIN:VCARD\nUID:{}\nEND:VCARD'.format(uid))
+    item = Item(f'BEGIN:VCARD\nUID:{uid}\nEND:VCARD')
     href, etag = s.upload(item)
     assert s.get(href)[0].uid == uid
     assert not href_safe(uid)
@@ -58,7 +60,7 @@ def test_repair_unsafe_uids(uid):
     ('perfectly-fine', 'b@dh0mbr3')
 ])
 def test_repair_unsafe_href(uid, href):
-    item = Item('BEGIN:VCARD\nUID:{}\nEND:VCARD'.format(uid))
+    item = Item(f'BEGIN:VCARD\nUID:{uid}\nEND:VCARD')
     new_item = repair_item(href, item, set(), True)
     assert new_item.raw != item.raw
     assert new_item.uid != item.uid
diff --git a/tests/unit/utils/test_vobject.py b/tests/unit/utils/test_vobject.py
index 84d87a8..44a5f8a 100644
--- a/tests/unit/utils/test_vobject.py
+++ b/tests/unit/utils/test_vobject.py
@@ -1,16 +1,20 @@
 from textwrap import dedent
 
 import hypothesis.strategies as st
-from hypothesis import assume, given
-from hypothesis.stateful import Bundle, RuleBasedStateMachine, rule
-
 import pytest
-
-from tests import BARE_EVENT_TEMPLATE, EVENT_TEMPLATE, \
-    EVENT_WITH_TIMEZONE_TEMPLATE, VCARD_TEMPLATE, normalize_item, \
-    uid_strategy
+from hypothesis import assume
+from hypothesis import given
+from hypothesis.stateful import Bundle
+from hypothesis.stateful import rule
+from hypothesis.stateful import RuleBasedStateMachine
 
 import vdirsyncer.vobject as vobject
+from tests import BARE_EVENT_TEMPLATE
+from tests import EVENT_TEMPLATE
+from tests import EVENT_WITH_TIMEZONE_TEMPLATE
+from tests import normalize_item
+from tests import uid_strategy
+from tests import VCARD_TEMPLATE
 
 
 _simple_split = [
@@ -221,7 +225,7 @@ def test_replace_uid(template, uid):
     item = vobject.Item(template.format(r=123, uid=123)).with_uid(uid)
     assert item.uid == uid
     if uid:
-        assert item.raw.count('\nUID:{}'.format(uid)) == 1
+        assert item.raw.count(f'\nUID:{uid}') == 1
     else:
         assert '\nUID:' not in item.raw
 
@@ -317,7 +321,7 @@ class VobjectMachine(RuleBasedStateMachine):
           params=st.lists(st.tuples(value_strategy, value_strategy)))
     def add_prop_raw(self, c, key, value, params):
         params_str = ','.join(k + '=' + v for k, v in params)
-        c.props.insert(0, '{};{}:{}'.format(key, params_str, value))
+        c.props.insert(0, f'{key};{params_str}:{value}')
         assert c[key] == value
         assert key in c
         assert c.get(key) == value
diff --git a/vdirsyncer/__init__.py b/vdirsyncer/__init__.py
index 84dbb69..dbdd529 100644
--- a/vdirsyncer/__init__.py
+++ b/vdirsyncer/__init__.py
@@ -19,8 +19,8 @@ except ImportError:  # pragma: no cover
 
 def _check_python_version():  # pragma: no cover
     import sys
-    if sys.version_info < (3, 4, 0):
-        print('vdirsyncer requires at least Python 3.5.')
+    if sys.version_info < (3, 7, 0):
+        print('vdirsyncer requires at least Python 3.7.')
         sys.exit(1)
 
 
diff --git a/vdirsyncer/cli/__init__.py b/vdirsyncer/cli/__init__.py
index 116759a..ff86502 100644
--- a/vdirsyncer/cli/__init__.py
+++ b/vdirsyncer/cli/__init__.py
@@ -3,10 +3,10 @@ import logging
 import sys
 
 import click
-
 import click_log
 
-from .. import BUGTRACKER_HOME, __version__
+from .. import __version__
+from .. import BUGTRACKER_HOME
 
 
 cli_logger = logging.getLogger(__name__)
@@ -65,7 +65,7 @@ def max_workers_callback(ctx, param, value):
     if value == 0 and logging.getLogger('vdirsyncer').level == logging.DEBUG:
         value = 1
 
-    cli_logger.debug('Using {} maximal workers.'.format(value))
+    cli_logger.debug(f'Using {value} maximal workers.')
     return value
 
 
@@ -75,7 +75,7 @@ def max_workers_option(default=0):
         help += 'The default is 0, which means "as many as necessary". ' \
                 'With -vdebug enabled, the default is 1.'
     else:
-        help += 'The default is {}.'.format(default)
+        help += f'The default is {default}.'
 
     return click.option(
         '--max-workers', default=default, type=click.IntRange(min=0, max=None),
diff --git a/vdirsyncer/cli/config.py b/vdirsyncer/cli/config.py
index 643e506..339bde9 100644
--- a/vdirsyncer/cli/config.py
+++ b/vdirsyncer/cli/config.py
@@ -6,10 +6,12 @@ from itertools import chain
 
 from click_threading import get_ui_worker
 
+from .. import exceptions
+from .. import PROJECT_HOME
+from ..utils import cached_property
+from ..utils import expand_path
 from .fetchparams import expand_fetch_params
 from .utils import storage_class_from_config
-from .. import PROJECT_HOME, exceptions
-from ..utils import cached_property, expand_path
 
 
 GENERAL_ALL = frozenset(['status_path'])
@@ -101,7 +103,7 @@ class _ConfigReader:
     def _parse_section(self, section_type, name, options):
         validate_section_name(name, section_type)
         if name in self._seen_names:
-            raise ValueError('Name "{}" already used.'.format(name))
+            raise ValueError(f'Name "{name}" already used.')
         self._seen_names.add(name)
 
         if section_type == 'general':
@@ -163,7 +165,7 @@ class Config:
             try:
                 self.pairs[name] = PairConfig(self, name, options)
             except ValueError as e:
-                raise exceptions.UserError('Pair {}: {}'.format(name, e))
+                raise exceptions.UserError(f'Pair {name}: {e}')
 
     @classmethod
     def from_fileobject(cls, f):
diff --git a/vdirsyncer/cli/discover.py b/vdirsyncer/cli/discover.py
index 30addc3..fdc8f9d 100644
--- a/vdirsyncer/cli/discover.py
+++ b/vdirsyncer/cli/discover.py
@@ -3,12 +3,14 @@ import json
 import logging
 import sys
 
-from .utils import handle_collection_not_found, handle_storage_init_error, \
-    load_status, save_status, storage_class_from_config, \
-    storage_instance_from_config
-
 from .. import exceptions
 from ..utils import cached_property
+from .utils import handle_collection_not_found
+from .utils import handle_storage_init_error
+from .utils import load_status
+from .utils import save_status
+from .utils import storage_class_from_config
+from .utils import storage_instance_from_config
 
 
 # Increase whenever upgrade potentially breaks discovery cache and collections
@@ -211,7 +213,7 @@ def _print_collections(instance_name, get_discovered):
         logger.warning('Failed to discover collections for {}, use `-vdebug` '
                        'to see the full traceback.'.format(instance_name))
         return
-    logger.info('{}:'.format(instance_name))
+    logger.info(f'{instance_name}:')
     for args in discovered.values():
         collection = args['collection']
         if collection is None:
@@ -226,7 +228,7 @@ def _print_collections(instance_name, get_discovered):
 
         logger.info('  - {}{}'.format(
             json.dumps(collection),
-            ' ("{}")'.format(displayname)
+            f' ("{displayname}")'
             if displayname and displayname != collection
             else ''
         ))
diff --git a/vdirsyncer/cli/fetchparams.py b/vdirsyncer/cli/fetchparams.py
index 346a14f..2f3e9b9 100644
--- a/vdirsyncer/cli/fetchparams.py
+++ b/vdirsyncer/cli/fetchparams.py
@@ -4,7 +4,8 @@ import click
 
 from . import AppContext
 from .. import exceptions
-from ..utils import expand_path, synchronized
+from ..utils import expand_path
+from ..utils import synchronized
 
 SUFFIX = '.fetch'
 
@@ -19,7 +20,7 @@ def expand_fetch_params(config):
 
         newkey = key[:-len(SUFFIX)]
         if newkey in config:
-            raise ValueError('Can\'t set {} and {}.'.format(key, newkey))
+            raise ValueError(f'Can\'t set {key} and {newkey}.')
         config[newkey] = _fetch_value(config[key], key)
         del config[key]
 
@@ -45,7 +46,7 @@ def _fetch_value(opts, key):
     cache_key = tuple(opts)
     if cache_key in password_cache:
         rv = password_cache[cache_key]
-        logger.debug('Found cached value for {!r}.'.format(opts))
+        logger.debug(f'Found cached value for {opts!r}.')
         if isinstance(rv, BaseException):
             raise rv
         return rv
@@ -54,7 +55,7 @@ def _fetch_value(opts, key):
     try:
         strategy_fn = STRATEGIES[strategy]
     except KeyError:
-        raise exceptions.UserError('Unknown strategy: {}'.format(strategy))
+        raise exceptions.UserError(f'Unknown strategy: {strategy}')
 
     logger.debug('Fetching value for {} with {} strategy.'
                  .format(key, strategy))
diff --git a/vdirsyncer/cli/tasks.py b/vdirsyncer/cli/tasks.py
index da7adc5..58e14e2 100644
--- a/vdirsyncer/cli/tasks.py
+++ b/vdirsyncer/cli/tasks.py
@@ -1,13 +1,19 @@
 import functools
 import json
 
+from .. import exceptions
+from .. import sync
 from .config import CollectionConfig
-from .discover import collections_for_pair, storage_class_from_config, \
-    storage_instance_from_config
-from .utils import JobFailed, cli_logger, get_status_name, \
-    handle_cli_error, load_status, manage_sync_status, save_status
-
-from .. import exceptions, sync
+from .discover import collections_for_pair
+from .discover import storage_class_from_config
+from .discover import storage_instance_from_config
+from .utils import cli_logger
+from .utils import get_status_name
+from .utils import handle_cli_error
+from .utils import JobFailed
+from .utils import load_status
+from .utils import manage_sync_status
+from .utils import save_status
 
 
 def prepare_pair(wq, pair_name, collections, config, callback, **kwargs):
@@ -45,7 +51,7 @@ def sync_collection(wq, collection, general, force_delete):
     status_name = get_status_name(pair.name, collection.name)
 
     try:
-        cli_logger.info('Syncing {}'.format(status_name))
+        cli_logger.info(f'Syncing {status_name}')
 
         a = storage_instance_from_config(collection.config_a)
         b = storage_instance_from_config(collection.config_b)
@@ -110,7 +116,7 @@ def repair_collection(config, collection, repair_unsafe_uid):
     config['type'] = storage_type
     storage = storage_instance_from_config(config)
 
-    cli_logger.info('Repairing {}/{}'.format(storage_name, collection))
+    cli_logger.info(f'Repairing {storage_name}/{collection}')
     cli_logger.warning('Make sure no other program is talking to the server.')
     repair_storage(storage, repair_unsafe_uid=repair_unsafe_uid)
 
@@ -121,7 +127,7 @@ def metasync_collection(wq, collection, general):
     status_name = get_status_name(pair.name, collection.name)
 
     try:
-        cli_logger.info('Metasyncing {}'.format(status_name))
+        cli_logger.info(f'Metasyncing {status_name}')
 
         status = load_status(general['status_path'], pair.name,
                              collection.name, data_type='metadata') or {}
diff --git a/vdirsyncer/cli/utils.py b/vdirsyncer/cli/utils.py
index 765c411..d8b420d 100644
--- a/vdirsyncer/cli/utils.py
+++ b/vdirsyncer/cli/utils.py
@@ -7,18 +7,21 @@ import os
 import queue
 import sys
 
+import click
+import click_threading
 from atomicwrites import atomic_write
 
-import click
-
-import click_threading
-
 from . import cli_logger
-from .. import BUGTRACKER_HOME, DOCS_HOME, exceptions
-from ..sync.exceptions import IdentConflict, PartialSync, StorageEmpty, \
-    SyncConflict
+from .. import BUGTRACKER_HOME
+from .. import DOCS_HOME
+from .. import exceptions
+from ..sync.exceptions import IdentConflict
+from ..sync.exceptions import PartialSync
+from ..sync.exceptions import StorageEmpty
+from ..sync.exceptions import SyncConflict
 from ..sync.status import SqliteStatus
-from ..utils import expand_path, get_storage_init_args
+from ..utils import expand_path
+from ..utils import get_storage_init_args
 
 
 STATUS_PERMISSIONS = 0o600
@@ -144,11 +147,11 @@ def handle_cli_error(status_name=None, e=None):
         import traceback
         tb = traceback.format_tb(tb)
         if status_name:
-            msg = 'Unknown error occurred for {}'.format(status_name)
+            msg = f'Unknown error occurred for {status_name}'
         else:
             msg = 'Unknown error occurred'
 
-        msg += ': {}\nUse `-vdebug` to see the full traceback.'.format(e)
+        msg += f': {e}\nUse `-vdebug` to see the full traceback.'
 
         cli_logger.error(msg)
         cli_logger.debug(''.join(tb))
@@ -210,8 +213,7 @@ def manage_sync_status(base_path, pair_name, collection_name):
         with open(path, 'rb') as f:
             if f.read(1) == b'{':
                 f.seek(0)
-                # json.load doesn't work on binary files for Python 3.5
-                legacy_status = dict(json.loads(f.read().decode('utf-8')))
+                legacy_status = dict(json.load(f))
     except (OSError, ValueError):
         pass
 
@@ -247,7 +249,7 @@ def storage_class_from_config(config):
         cls = storage_names[storage_name]
     except KeyError:
         raise exceptions.UserError(
-            'Unknown storage type: {}'.format(storage_name))
+            f'Unknown storage type: {storage_name}')
     return cls, config
 
 
@@ -399,7 +401,7 @@ def handle_collection_not_found(config, collection, e=None):
     storage_name = config.get('instance_name', None)
 
     cli_logger.warning('{}No collection {} found for storage {}.'
-                       .format('{}\n'.format(e) if e else '',
+                       .format(f'{e}\n' if e else '',
                                json.dumps(collection), storage_name))
 
     if click.confirm('Should vdirsyncer attempt to create it?'):
diff --git a/vdirsyncer/exceptions.py b/vdirsyncer/exceptions.py
index 5644b54..b21cd27 100644
--- a/vdirsyncer/exceptions.py
+++ b/vdirsyncer/exceptions.py
@@ -10,7 +10,7 @@ class Error(Exception):
     def __init__(self, *args, **kwargs):
         for key, value in kwargs.items():
             if getattr(self, key, object()) is not None:  # pragma: no cover
-                raise TypeError('Invalid argument: {}'.format(key))
+                raise TypeError(f'Invalid argument: {key}')
             setattr(self, key, value)
 
         super().__init__(*args)
@@ -25,7 +25,7 @@ class UserError(Error, ValueError):
     def __str__(self):
         msg = Error.__str__(self)
         for problem in self.problems or ():
-            msg += '\n  - {}'.format(problem)
+            msg += f'\n  - {problem}'
 
         return msg
 
diff --git a/vdirsyncer/http.py b/vdirsyncer/http.py
index 5cb6204..63a5dbf 100644
--- a/vdirsyncer/http.py
+++ b/vdirsyncer/http.py
@@ -2,12 +2,14 @@ import logging
 
 import requests
 
+from . import __version__
+from . import DOCS_HOME
+from . import exceptions
 from .utils import expand_path
-from . import DOCS_HOME, exceptions, __version__
 
 
 logger = logging.getLogger(__name__)
-USERAGENT = 'vdirsyncer/{}'.format(__version__)
+USERAGENT = f'vdirsyncer/{__version__}'
 
 
 def _detect_faulty_requests():  # pragma: no cover
@@ -133,7 +135,7 @@ def request(method, url, session=None, latin1_fallback=True,
 
     func = session.request
 
-    logger.debug('{} {}'.format(method, url))
+    logger.debug(f'{method} {url}')
     logger.debug(kwargs.get('headers', {}))
     logger.debug(kwargs.get('data', None))
     logger.debug('Sending request...')
diff --git a/vdirsyncer/metasync.py b/vdirsyncer/metasync.py
index 875f255..82a4556 100644
--- a/vdirsyncer/metasync.py
+++ b/vdirsyncer/metasync.py
@@ -16,12 +16,12 @@ class MetaSyncConflict(MetaSyncError):
 
 def metasync(storage_a, storage_b, status, keys, conflict_resolution=None):
     def _a_to_b():
-        logger.info('Copying {} to {}'.format(key, storage_b))
+        logger.info(f'Copying {key} to {storage_b}')
         storage_b.set_meta(key, a)
         status[key] = a
 
     def _b_to_a():
-        logger.info('Copying {} to {}'.format(key, storage_a))
+        logger.info(f'Copying {key} to {storage_a}')
         storage_a.set_meta(key, b)
         status[key] = b
 
@@ -45,10 +45,10 @@ def metasync(storage_a, storage_b, status, keys, conflict_resolution=None):
         a = storage_a.get_meta(key)
         b = storage_b.get_meta(key)
         s = normalize_meta_value(status.get(key))
-        logger.debug('Key: {}'.format(key))
-        logger.debug('A: {}'.format(a))
-        logger.debug('B: {}'.format(b))
-        logger.debug('S: {}'.format(s))
+        logger.debug(f'Key: {key}')
+        logger.debug(f'A: {a}')
+        logger.debug(f'B: {b}')
+        logger.debug(f'S: {s}')
 
         if a != s and b != s:
             _resolve_conflict()
diff --git a/vdirsyncer/repair.py b/vdirsyncer/repair.py
index 6c8b257..3c94847 100644
--- a/vdirsyncer/repair.py
+++ b/vdirsyncer/repair.py
@@ -1,7 +1,8 @@
 import logging
 from os.path import basename
 
-from .utils import generate_href, href_safe
+from .utils import generate_href
+from .utils import href_safe
 
 logger = logging.getLogger(__name__)
 
@@ -25,7 +26,7 @@ def repair_storage(storage, repair_unsafe_uid):
                          'The PRODID property may indicate which software '
                          'created this item.'
                          .format(href))
-            logger.error('Item content: {!r}'.format(item.raw))
+            logger.error(f'Item content: {item.raw!r}')
             continue
 
         seen_uids.add(new_item.uid)
diff --git a/vdirsyncer/storage/base.py b/vdirsyncer/storage/base.py
index 7dfcbdd..b78f828 100644
--- a/vdirsyncer/storage/base.py
+++ b/vdirsyncer/storage/base.py
@@ -71,7 +71,7 @@ class Storage(metaclass=StorageMeta):
         self.read_only = bool(read_only)
 
         if collection and instance_name:
-            instance_name = '{}/{}'.format(instance_name, collection)
+            instance_name = f'{instance_name}/{collection}'
         self.instance_name = instance_name
         self.collection = collection
 
diff --git a/vdirsyncer/storage/dav.py b/vdirsyncer/storage/dav.py
index a3becb7..a7e2422 100644
--- a/vdirsyncer/storage/dav.py
+++ b/vdirsyncer/storage/dav.py
@@ -2,17 +2,21 @@ import datetime
 import logging
 import urllib.parse as urlparse
 import xml.etree.ElementTree as etree
-
 from inspect import getfullargspec
 
 import requests
 from requests.exceptions import HTTPError
 
-from .base import Storage, normalize_meta_value
-from .. import exceptions, http, utils
-from ..http import USERAGENT, prepare_auth, \
-    prepare_client_cert, prepare_verify
+from .. import exceptions
+from .. import http
+from .. import utils
+from ..http import prepare_auth
+from ..http import prepare_client_cert
+from ..http import prepare_verify
+from ..http import USERAGENT
 from ..vobject import Item
+from .base import normalize_meta_value
+from .base import Storage
 
 
 dav_logger = logging.getLogger(__name__)
@@ -34,7 +38,7 @@ del _generate_path_reserved_chars
 def _contains_quoted_reserved_chars(x):
     for y in _path_reserved_chars:
         if y in x:
-            dav_logger.debug('Unsafe character: {!r}'.format(y))
+            dav_logger.debug(f'Unsafe character: {y!r}')
             return True
     return False
 
@@ -52,7 +56,7 @@ def _assert_multistatus_success(r):
         except (ValueError, IndexError):
             continue
         if st < 200 or st >= 400:
-            raise HTTPError('Server error: {}'.format(st))
+            raise HTTPError(f'Server error: {st}')
 
 
 def _normalize_href(base, href):
@@ -78,7 +82,7 @@ def _normalize_href(base, href):
     x = urlparse.quote(x, '/@%:')
 
     if orig_href == x:
-        dav_logger.debug('Already normalized: {!r}'.format(x))
+        dav_logger.debug(f'Already normalized: {x!r}')
     else:
         dav_logger.debug('Normalized URL from {!r} to {!r}'
                          .format(orig_href, x))
@@ -120,7 +124,7 @@ def _merge_xml(items):
         return None
     rv = items[0]
     for item in items[1:]:
-        rv.extend(item.getiterator())
+        rv.extend(item.iter())
     return rv
 
 
@@ -459,7 +463,7 @@ class DAVStorage(Storage):
         for href in hrefs:
             if href != self._normalize_href(href):
                 raise exceptions.NotFoundError(href)
-            href_xml.append('<D:href>{}</D:href>'.format(href))
+            href_xml.append(f'<D:href>{href}</D:href>')
         if not href_xml:
             return ()
 
@@ -591,7 +595,7 @@ class DAVStorage(Storage):
                 props = _merge_xml(props)
 
             if props.find('{DAV:}resourcetype/{DAV:}collection') is not None:
-                dav_logger.debug('Skipping {!r}, is collection.'.format(href))
+                dav_logger.debug(f'Skipping {href!r}, is collection.')
                 continue
 
             etag = getattr(props.find('{DAV:}getetag'), 'text', '')
@@ -641,7 +645,7 @@ class DAVStorage(Storage):
         except KeyError:
             raise exceptions.UnsupportedMetadataError()
 
-        xpath = '{{{}}}{}'.format(namespace, tagname)
+        xpath = f'{{{namespace}}}{tagname}'
         data = '''<?xml version="1.0" encoding="utf-8" ?>
             <D:propfind xmlns:D="DAV:">
                 <D:prop>
@@ -674,7 +678,7 @@ class DAVStorage(Storage):
         except KeyError:
             raise exceptions.UnsupportedMetadataError()
 
-        lxml_selector = '{{{}}}{}'.format(namespace, tagname)
+        lxml_selector = f'{{{namespace}}}{tagname}'
         element = etree.Element(lxml_selector)
         element.text = normalize_meta_value(value)
 
diff --git a/vdirsyncer/storage/etesync.py b/vdirsyncer/storage/etesync.py
index 80339d1..88bf07c 100644
--- a/vdirsyncer/storage/etesync.py
+++ b/vdirsyncer/storage/etesync.py
@@ -1,8 +1,8 @@
+import binascii
 import contextlib
 import functools
 import logging
 import os
-import binascii
 
 import atomicwrites
 import click
@@ -66,7 +66,7 @@ class _Session:
         key = self._get_key()
         if not key:
             password = click.prompt('Enter key password', hide_input=True)
-            click.echo('Deriving key for {}'.format(self.email))
+            click.echo(f'Deriving key for {self.email}')
             self.etesync.derive_key(password)
             self._set_key(self.etesync.cipher_key)
         else:
@@ -134,7 +134,7 @@ class EtesyncStorage(Storage):
                     **kwargs
                 )
             else:
-                logger.debug('Skipping collection: {!r}'.format(entry))
+                logger.debug(f'Skipping collection: {entry!r}')
 
     @classmethod
     def create_collection(cls, collection, email, secrets_dir, server_url=None,
diff --git a/vdirsyncer/storage/filesystem.py b/vdirsyncer/storage/filesystem.py
index 8859bbc..b398119 100644
--- a/vdirsyncer/storage/filesystem.py
+++ b/vdirsyncer/storage/filesystem.py
@@ -5,10 +5,14 @@ import subprocess
 
 from atomicwrites import atomic_write
 
-from .base import Storage, normalize_meta_value
 from .. import exceptions
-from ..utils import checkdir, expand_path, generate_href, get_etag_from_file
+from ..utils import checkdir
+from ..utils import expand_path
+from ..utils import generate_href
+from ..utils import get_etag_from_file
 from ..vobject import Item
+from .base import normalize_meta_value
+from .base import Storage
 
 logger = logging.getLogger(__name__)
 
diff --git a/vdirsyncer/storage/google.py b/vdirsyncer/storage/google.py
index f09ff48..675c273 100644
--- a/vdirsyncer/storage/google.py
+++ b/vdirsyncer/storage/google.py
@@ -3,15 +3,16 @@ import logging
 import os
 import urllib.parse as urlparse
 
-from atomicwrites import atomic_write
-
 import click
-
+from atomicwrites import atomic_write
 from click_threading import get_ui_worker
 
-from . import base, dav
+from . import base
+from . import dav
 from .. import exceptions
-from ..utils import checkdir, expand_path, open_graphical_browser
+from ..utils import checkdir
+from ..utils import expand_path
+from ..utils import open_graphical_browser
 
 logger = logging.getLogger(__name__)
 
@@ -80,7 +81,7 @@ class GoogleSession(dav.DAVSession):
                 # access_type and approval_prompt are Google specific
                 # extra parameters.
                 access_type='offline', approval_prompt='force')
-            click.echo('Opening {} ...'.format(authorization_url))
+            click.echo(f'Opening {authorization_url} ...')
             try:
                 open_graphical_browser(authorization_url)
             except Exception as e:
diff --git a/vdirsyncer/storage/http.py b/vdirsyncer/storage/http.py
index b9f12e9..e3ca984 100644
--- a/vdirsyncer/storage/http.py
+++ b/vdirsyncer/storage/http.py
@@ -1,10 +1,14 @@
 import urllib.parse as urlparse
 
-from .base import Storage
 from .. import exceptions
-from ..http import USERAGENT, prepare_auth, \
-    prepare_client_cert, prepare_verify, request
-from ..vobject import Item, split_collection
+from ..http import prepare_auth
+from ..http import prepare_client_cert
+from ..http import prepare_verify
+from ..http import request
+from ..http import USERAGENT
+from ..vobject import Item
+from ..vobject import split_collection
+from .base import Storage
 
 
 class HttpStorage(Storage):
diff --git a/vdirsyncer/storage/memory.py b/vdirsyncer/storage/memory.py
index 74b58e8..e953691 100644
--- a/vdirsyncer/storage/memory.py
+++ b/vdirsyncer/storage/memory.py
@@ -1,12 +1,12 @@
 import random
 
-from .base import Storage, normalize_meta_value
-
 from .. import exceptions
+from .base import normalize_meta_value
+from .base import Storage
 
 
 def _random_string():
-    return '{:.9f}'.format(random.random())
+    return f'{random.random():.9f}'
 
 
 class MemoryStorage(Storage):
diff --git a/vdirsyncer/storage/singlefile.py b/vdirsyncer/storage/singlefile.py
index 5a56aef..829204c 100644
--- a/vdirsyncer/storage/singlefile.py
+++ b/vdirsyncer/storage/singlefile.py
@@ -7,10 +7,14 @@ import os
 
 from atomicwrites import atomic_write
 
-from .base import Storage
 from .. import exceptions
-from ..utils import checkfile, expand_path, get_etag_from_file
-from ..vobject import Item, join_collection, split_collection
+from ..utils import checkfile
+from ..utils import expand_path
+from ..utils import get_etag_from_file
+from ..vobject import Item
+from ..vobject import join_collection
+from ..vobject import split_collection
+from .base import Storage
 
 logger = logging.getLogger(__name__)
 
diff --git a/vdirsyncer/sync/__init__.py b/vdirsyncer/sync/__init__.py
index bdb945d..2119063 100644
--- a/vdirsyncer/sync/__init__.py
+++ b/vdirsyncer/sync/__init__.py
@@ -15,10 +15,13 @@ import logging
 
 from ..exceptions import UserError
 from ..utils import uniq
-
-from .status import SubStatus, ItemMetadata
-from .exceptions import BothReadOnly, IdentAlreadyExists, PartialSync, \
-    StorageEmpty, SyncConflict
+from .exceptions import BothReadOnly
+from .exceptions import IdentAlreadyExists
+from .exceptions import PartialSync
+from .exceptions import StorageEmpty
+from .exceptions import SyncConflict
+from .status import ItemMetadata
+from .status import SubStatus
 
 sync_logger = logging.getLogger(__name__)
 
diff --git a/vdirsyncer/sync/status.py b/vdirsyncer/sync/status.py
index 2544680..48b5634 100644
--- a/vdirsyncer/sync/status.py
+++ b/vdirsyncer/sync/status.py
@@ -1,7 +1,7 @@
 import abc
 import contextlib
-import sys
 import sqlite3
+import sys
 
 from .exceptions import IdentAlreadyExists
 
diff --git a/vdirsyncer/utils.py b/vdirsyncer/utils.py
index 5559ec3..8730519 100644
--- a/vdirsyncer/utils.py
+++ b/vdirsyncer/utils.py
@@ -2,7 +2,6 @@ import functools
 import os
 import sys
 import uuid
-
 from inspect import getfullargspec
 
 from . import exceptions
@@ -73,7 +72,7 @@ def get_etag_from_file(f):
     mtime = getattr(stat, 'st_mtime_ns', None)
     if mtime is None:
         mtime = stat.st_mtime
-    return '{:.9f};{}'.format(mtime, stat.st_ino)
+    return f'{mtime:.9f};{stat.st_ino}'
 
 
 def get_storage_init_specs(cls, stop_at=object):
@@ -125,7 +124,7 @@ def checkdir(path, create=False, mode=0o750):
 
     if not os.path.isdir(path):
         if os.path.exists(path):
-            raise OSError('{} is not a directory.'.format(path))
+            raise OSError(f'{path} is not a directory.')
         if create:
             os.makedirs(path, mode)
         else:
@@ -143,7 +142,7 @@ def checkfile(path, create=False):
     checkdir(os.path.dirname(path), create=create)
     if not os.path.isfile(path):
         if os.path.exists(path):
-            raise OSError('{} is not a file.'.format(path))
+            raise OSError(f'{path} is not a file.')
         if create:
             with open(path, 'wb'):
                 pass
diff --git a/vdirsyncer/vobject.py b/vdirsyncer/vobject.py
index 521e97c..92e46d2 100644
--- a/vdirsyncer/vobject.py
+++ b/vdirsyncer/vobject.py
@@ -1,7 +1,9 @@
 import hashlib
-from itertools import chain, tee
+from itertools import chain
+from itertools import tee
 
-from .utils import cached_property, uniq
+from .utils import cached_property
+from .utils import uniq
 
 
 IGNORE_PROPS = (
@@ -205,14 +207,14 @@ def join_collection(items, wrappers=_default_join_wrappers):
 
     if wrapper_type is not None:
         lines = chain(*(
-            ['BEGIN:{}'.format(wrapper_type)],
+            [f'BEGIN:{wrapper_type}'],
             # XXX: wrapper_props is a list of lines (with line-wrapping), so
             # filtering out duplicate lines will almost certainly break
             # multiline-values.  Since the only props we usually need to
             # support are PRODID and VERSION, I don't care.
             uniq(wrapper_props),
             lines,
-            ['END:{}'.format(wrapper_type)]
+            [f'END:{wrapper_type}']
         ))
     return ''.join(line + '\r\n' for line in lines)
 
@@ -299,14 +301,14 @@ class _Component:
             return rv[0]
 
     def dump_lines(self):
-        yield 'BEGIN:{}'.format(self.name)
+        yield f'BEGIN:{self.name}'
         yield from self.props
         for c in self.subcomponents:
             yield from c.dump_lines()
-        yield 'END:{}'.format(self.name)
+        yield f'END:{self.name}'
 
     def __delitem__(self, key):
-        prefix = ('{}:'.format(key), '{};'.format(key))
+        prefix = (f'{key}:', f'{key};')
         new_lines = []
         lineiter = iter(self.props)
         while True:
@@ -329,7 +331,7 @@ class _Component:
         assert isinstance(val, str)
         assert '\n' not in val
         del self[key]
-        line = '{}:{}'.format(key, val)
+        line = f'{key}:{val}'
         self.props.append(line)
 
     def __contains__(self, obj):
@@ -342,8 +344,8 @@ class _Component:
             raise ValueError(obj)
 
     def __getitem__(self, key):
-        prefix_without_params = '{}:'.format(key)
-        prefix_with_params = '{};'.format(key)
+        prefix_without_params = f'{key}:'
+        prefix_with_params = f'{key};'
         iterlines = iter(self.props)
         for line in iterlines:
             if line.startswith(prefix_without_params):