diff --git a/radicale/__init__.py b/radicale/__init__.py
index c0d762b..a036b4e 100644
--- a/radicale/__init__.py
+++ b/radicale/__init__.py
@@ -264,9 +264,6 @@ class Application(object):
 
         path = environ["PATH_INFO"]
 
-        # Find collection(s)
-        items = ical.Collection.from_path(path, environ.get("HTTP_DEPTH", "0"))
-
         # Get function corresponding to method
         function = getattr(self, environ["REQUEST_METHOD"].lower())
 
@@ -280,17 +277,21 @@ class Application(object):
         else:
             user = password = None
 
-        read_allowed_items, write_allowed_items = \
-            self.collect_allowed_items(items, user)
-
         is_authenticated = auth.is_authenticated(user, password)
+        is_valid_user = is_authenticated or not user
 
-        if ((read_allowed_items or write_allowed_items)
-            and (not user or is_authenticated)) or \
-                (is_authenticated and function == self.propfind) or \
-                function == self.options or not items:
-            # Collections found, or authenticated PROPFIND request,
-            # or OPTIONS request, or no items at all
+        if is_valid_user:
+            items = ical.Collection.from_path(path,
+                                              environ.get("HTTP_DEPTH", "0"))
+            read_allowed_items, write_allowed_items = \
+                self.collect_allowed_items(items, user)
+        else:
+            read_allowed_items, write_allowed_items = None, None
+
+        if is_valid_user and (
+                (read_allowed_items or write_allowed_items) or
+                (is_authenticated and function == self.propfind) or
+                function == self.options):
             status, headers, answer = function(
                 environ, read_allowed_items, write_allowed_items, content,
                 user)