diff --git a/radicale/item/__init__.py b/radicale/item/__init__.py
index 4a3fc22e..b0cef222 100644
--- a/radicale/item/__init__.py
+++ b/radicale/item/__init__.py
@@ -164,7 +164,7 @@ def check_and_sanitize_items(
                 ref_value_param = component.dtstart.params.get("VALUE")
                 for dates in chain(component.contents.get("exdate", []),
                                    component.contents.get("rdate", [])):
-                    if all(type(d) == type(ref_date) for d in dates.value):
+                    if all(type(d) is type(ref_date) for d in dates.value):
                         continue
                     for i, date in enumerate(dates.value):
                         dates.value[i] = ref_date.replace(
diff --git a/radicale/storage/multifilesystem/base.py b/radicale/storage/multifilesystem/base.py
index 7b1b7d28..bbb02198 100644
--- a/radicale/storage/multifilesystem/base.py
+++ b/radicale/storage/multifilesystem/base.py
@@ -44,7 +44,8 @@ class CollectionBase(storage.BaseCollection):
             filesystem_path = pathutils.path_to_filesystem(folder, self.path)
         self._filesystem_path = filesystem_path
 
-    @types.contextmanager
+    # TODO: better fix for "mypy"
+    @types.contextmanager  # type: ignore
     def _atomic_write(self, path: str, mode: str = "w",
                       newline: Optional[str] = None) -> Iterator[IO[AnyStr]]:
         # TODO: Overload with Literal when dropping support for Python < 3.8
diff --git a/radicale/storage/multifilesystem/cache.py b/radicale/storage/multifilesystem/cache.py
index 9cb4dda6..31ab4715 100644
--- a/radicale/storage/multifilesystem/cache.py
+++ b/radicale/storage/multifilesystem/cache.py
@@ -86,7 +86,8 @@ class CollectionPartCache(CollectionBase):
         content = self._item_cache_content(item)
         self._storage._makedirs_synced(cache_folder)
         # Race: Other processes might have created and locked the file.
-        with contextlib.suppress(PermissionError), self._atomic_write(
+        # TODO: better fix for "mypy"
+        with contextlib.suppress(PermissionError), self._atomic_write(  # type: ignore
                 os.path.join(cache_folder, href), "wb") as fo:
             fb = cast(BinaryIO, fo)
             pickle.dump((cache_hash, *content), fb)
diff --git a/radicale/storage/multifilesystem/meta.py b/radicale/storage/multifilesystem/meta.py
index edce6513..b95fb162 100644
--- a/radicale/storage/multifilesystem/meta.py
+++ b/radicale/storage/multifilesystem/meta.py
@@ -61,6 +61,7 @@ class CollectionPartMeta(CollectionBase):
         return self._meta_cache if key is None else self._meta_cache.get(key)
 
     def set_meta(self, props: Mapping[str, str]) -> None:
-        with self._atomic_write(self._props_path, "w") as fo:
+        # TODO: better fix for "mypy"
+        with self._atomic_write(self._props_path, "w") as fo:  # type: ignore
             f = cast(TextIO, fo)
             json.dump(props, f, sort_keys=True)
diff --git a/radicale/storage/multifilesystem/sync.py b/radicale/storage/multifilesystem/sync.py
index 83cbe2a0..ae703c91 100644
--- a/radicale/storage/multifilesystem/sync.py
+++ b/radicale/storage/multifilesystem/sync.py
@@ -95,7 +95,8 @@ class CollectionPartSync(CollectionPartCache, CollectionPartHistory,
             self._storage._makedirs_synced(token_folder)
             try:
                 # Race: Other processes might have created and locked the file.
-                with self._atomic_write(token_path, "wb") as fo:
+                # TODO: better fix for "mypy"
+                with self._atomic_write(token_path, "wb") as fo:  # type: ignore
                     fb = cast(BinaryIO, fo)
                     pickle.dump(state, fb)
             except PermissionError:
diff --git a/radicale/storage/multifilesystem/upload.py b/radicale/storage/multifilesystem/upload.py
index 730e4cb2..a9fcdc2c 100644
--- a/radicale/storage/multifilesystem/upload.py
+++ b/radicale/storage/multifilesystem/upload.py
@@ -43,7 +43,8 @@ class CollectionPartUpload(CollectionPartGet, CollectionPartCache,
             raise ValueError("Failed to store item %r in collection %r: %s" %
                              (href, self.path, e)) from e
         path = pathutils.path_to_filesystem(self._filesystem_path, href)
-        with self._atomic_write(path, newline="") as fo:
+        # TODO: better fix for "mypy"
+        with self._atomic_write(path, newline="") as fo:  # type: ignore
             f = cast(TextIO, fo)
             f.write(item.serialize())
         # Clean the cache after the actual item is stored, or the cache entry
diff --git a/radicale/tests/test_server.py b/radicale/tests/test_server.py
index 73c73e0e..67ce10d4 100644
--- a/radicale/tests/test_server.py
+++ b/radicale/tests/test_server.py
@@ -106,7 +106,10 @@ class TestBaseServerRequests(BaseTest):
         data_bytes = None
         if data:
             data_bytes = data.encode(encoding)
-        req_host = ("[%s]" % self.sockname[0]) if self.sockfamily == socket.AF_INET6 else self.sockname[0]
+        if self.sockfamily == socket.AF_INET6:
+            req_host = ("[%s]" % self.sockname[0])
+        else:
+            req_host = self.sockname[0]
         req = request.Request(
             "%s://%s:%d%s" % (scheme, req_host, self.sockname[1], path),
             data=data_bytes, headers=headers, method=method)
diff --git a/setup.cfg b/setup.cfg
index fe2038fb..4326cd97 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,7 +30,7 @@ known_third_party = defusedxml,passlib,pkg_resources,pytest,vobject
 # Only enable default tests (https://github.com/PyCQA/flake8/issues/790#issuecomment-812823398)
 # DNE: DOES-NOT-EXIST
 select = E,F,W,C90,DNE000
-ignore = E121,E123,E126,E226,E24,E704,W503,W504,DNE000
+ignore = E121,E123,E126,E226,E24,E704,W503,W504,DNE000,E501
 extend-exclude = build
 
 [mypy]