diff --git a/examples/xandikos.nginx.conf b/examples/xandikos.nginx.conf
index 97acc423..c1fa50a8 100644
--- a/examples/xandikos.nginx.conf
+++ b/examples/xandikos.nginx.conf
@@ -18,6 +18,7 @@ server {
     location / {
         proxy_set_header Host $http_host;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header X-Remote-User $remote_user;
         proxy_redirect off;
         proxy_buffering off;
         proxy_pass http://xandikos;
diff --git a/notes/api-stability.rst b/notes/api-stability.rst
index 54b097b5..1167dfa2 100644
--- a/notes/api-stability.rst
+++ b/notes/api-stability.rst
@@ -4,7 +4,7 @@ API Stability
 There are currently no guarantees about Xandikos Python APIs staying the same
 across different versions, except the following APIs:
 
-xandikos.web.XandikosBackend(path)
+xandikos.web.XandikosBackend(path, autocreate)
 xandikos.web.XandikosBackend.create_principal(principal, create_defaults=False)
 xandikos.web.XandikosApp(backend, current_user_principal)
 xandikos.web.WellknownRedirector(app, path)
diff --git a/xandikos/tests/test_api.py b/xandikos/tests/test_api.py
index 6c515d80..b44d6999 100644
--- a/xandikos/tests/test_api.py
+++ b/xandikos/tests/test_api.py
@@ -35,7 +35,7 @@ class WebTests(unittest.TestCase):
     def test_backend(self):
         path = tempfile.mkdtemp()
         try:
-            backend = XandikosBackend(path)
+            backend = XandikosBackend(path=path, autocreate=True)
             backend.create_principal("foo", create_defaults=True)
             XandikosApp(backend, "foo")
         finally:
diff --git a/xandikos/tests/test_web.py b/xandikos/tests/test_web.py
index 6348bd26..eaec8e9d 100644
--- a/xandikos/tests/test_web.py
+++ b/xandikos/tests/test_web.py
@@ -57,7 +57,7 @@ def setUp(self):
 
         self.store = VdirStore.create(os.path.join(self.tempdir, "c"))
         self.store.load_extra_file_handler(ICalendarFile)
-        self.backend = XandikosBackend(self.tempdir)
+        self.backend = XandikosBackend(path=self.tempdir, autocreate=False)
 
         self.cal = CalendarCollection(self.backend, "c", self.store)
 
diff --git a/xandikos/web.py b/xandikos/web.py
index ed8700d0..f8269726 100644
--- a/xandikos/web.py
+++ b/xandikos/web.py
@@ -977,8 +977,9 @@ def open_store_from_path(path: str):
 
 
 class XandikosBackend(webdav.Backend):
-    def __init__(self, path):
+    def __init__(self, path, autocreate):
         self.path = path
+        self.autocreate = autocreate
         self._user_principals = set()
 
     def _map_to_file_path(self, relpath):
@@ -1040,6 +1041,15 @@ def get_resource(self, relpath):
             except KeyError:
                 return None
 
+    def set_principal(self, user):
+        principal = "/%s/" % user
+        if not self.get_resource(principal):
+            if self.autocreate:
+                self.create_principal(
+                    principal, create_defaults=True
+                )
+        self._mark_as_principal(principal)
+
 
 class XandikosApp(webdav.WebDAVApp):
     """A wsgi App that provides a Xandikos web server."""
@@ -1252,7 +1262,7 @@ def run_simple_server(
       port: TCP Port to listen on (None to disable)
       socket_path: Unix domain socket path to listen on (None to disable)
     """
-    backend = XandikosBackend(directory)
+    backend = XandikosBackend(directory, autocreate)
     backend._mark_as_principal(current_user_principal)
 
     if autocreate or defaults:
@@ -1415,7 +1425,8 @@ def main(argv=None):  # noqa: C901
 
     logging.basicConfig(level=logging.INFO, format='%(message)s')
 
-    backend = XandikosBackend(os.path.abspath(options.directory))
+    backend = XandikosBackend(os.path.abspath(options.directory),
+                              options.autocreate)
     backend._mark_as_principal(options.current_user_principal)
 
     if options.autocreate or options.defaults:
diff --git a/xandikos/webdav.py b/xandikos/webdav.py
index 7e69c4a3..d3f504bd 100644
--- a/xandikos/webdav.py
+++ b/xandikos/webdav.py
@@ -2101,7 +2101,12 @@ def handle_wsgi_request(self, environ, start_response):
             logging.debug('SCRIPT_NAME not set; assuming "".')
             environ["SCRIPT_NAME"] = ""
         request = WSGIRequest(environ)
+        remote_user = environ.get("HTTP_X_REMOTE_USER")
         environ = {"SCRIPT_NAME": environ["SCRIPT_NAME"]}
+        if remote_user:
+            environ["REMOTE_USER"] = remote_user
+            self.backend.set_principal(remote_user)
+
         try:
             loop = asyncio.get_event_loop()
         except RuntimeError:
diff --git a/xandikos/wsgi.py b/xandikos/wsgi.py
index 5b4b1d89..bcd5203b 100644
--- a/xandikos/wsgi.py
+++ b/xandikos/wsgi.py
@@ -29,7 +29,8 @@
 )
 
 
-backend = XandikosBackend(path=os.environ["XANDIKOSPATH"])
+backend = XandikosBackend(path=os.environ["XANDIKOSPATH"],
+                          autocreate=os.getenv("AUTOCREATE"))
 if not os.path.isdir(backend.path):
     if os.getenv("AUTOCREATE"):
         os.makedirs(os.environ["XANDIKOSPATH"])