diff --git a/radicale/__init__.py b/radicale/__init__.py
index 9331821..90b0752 100644
--- a/radicale/__init__.py
+++ b/radicale/__init__.py
@@ -321,9 +321,9 @@ class Application:
             content = None
 
         if is_valid_user:
-            if function in (self.do_GET, self.do_HEAD,
-                            self.do_OPTIONS, self.do_PROPFIND,
-                            self.do_REPORT):
+            if function in (
+                    self.do_GET, self.do_HEAD, self.do_OPTIONS,
+                    self.do_PROPFIND, self.do_REPORT):
                 lock_mode = "r"
             else:
                 lock_mode = "w"
diff --git a/radicale/storage.py b/radicale/storage.py
index 446d7bb..30859cf 100644
--- a/radicale/storage.py
+++ b/radicale/storage.py
@@ -385,8 +385,7 @@ class Collection(BaseCollection):
             _, directories, _ = next(os.walk(collection._filesystem_path))
             for sub_path in directories:
                 if not is_safe_filesystem_path_component(sub_path):
-                    cls.logger.debug(
-                        "Skipping collection: %s", sub_path)
+                    cls.logger.debug("Skipping collection: %s", sub_path)
                     continue
                 full_path = os.path.join(collection._filesystem_path, sub_path)
                 if os.path.exists(full_path):
@@ -441,8 +440,7 @@ class Collection(BaseCollection):
 
         for href in hrefs:
             if not is_safe_filesystem_path_component(href):
-                self.logger.debug(
-                    "Skipping component: %s", href)
+                self.logger.debug("Skipping component: %s", href)
                 continue
             path = os.path.join(self._filesystem_path, href)
             if not href.endswith(".props") and os.path.isfile(path):
@@ -560,6 +558,9 @@ class Collection(BaseCollection):
             return None
         items = []
         for href in os.listdir(self._filesystem_path):
+            if not is_safe_filesystem_path_component(href):
+                self.logger.debug("Skipping component: %s", href)
+                continue
             path = os.path.join(self._filesystem_path, href)
             if os.path.isfile(path) and not path.endswith(".props"):
                 with open(path, encoding=self.storage_encoding) as fd:
diff --git a/radicale/xmlutils.py b/radicale/xmlutils.py
index b57f08d..bf3fff9 100644
--- a/radicale/xmlutils.py
+++ b/radicale/xmlutils.py
@@ -505,8 +505,7 @@ def delete(path, collection):
     return _pretty_xml(multistatus)
 
 
-def propfind(path, xml_request, read_collections, write_collections,
-             user=None):
+def propfind(path, xml_request, read_collections, write_collections, user):
     """Read and answer PROPFIND requests.
 
     Read rfc4918-9.1 for info.
@@ -552,7 +551,7 @@ def _propfind_response(path, item, props, user, write=False):
     # TODO: fix this
     is_collection = hasattr(item, "list")
     if is_collection:
-        is_leaf = bool(item.list())
+        is_leaf = bool(item.get_meta("tag"))
         collection = item
     else:
         collection = item.collection
@@ -671,16 +670,7 @@ def _propfind_response(path, item, props, user, write=False):
                 elif tag == _tag("CS", "getctag"):
                     element.text = item.etag
                 elif tag == _tag("C", "calendar-timezone"):
-                    timezones = set()
-                    for href, _ in item.list():
-                        event = item.get(href)
-                        if "vtimezone" in event.contents:
-                            for timezone_ in event.vtimezone_list:
-                                timezones.add(timezone_)
-                    timezone_collection = vobject.iCalendar()
-                    for timezone_ in timezones:
-                        timezone_collection.add(timezone_)
-                    element.text = timezone_collection.serialize()
+                    element.text = item.get_meta("C:calendar-timezone")
                 elif tag == _tag("D", "displayname"):
                     element.text = item.get_meta("D:displayname") or item.path
                 elif tag == _tag("ICAL", "calendar-color"):