diff --git a/src/borg/archive.py b/src/borg/archive.py
index 212fd3bfa..86e8a62e0 100644
--- a/src/borg/archive.py
+++ b/src/borg/archive.py
@@ -239,7 +239,9 @@ def OsOpen(*, flags, path=None, parent_fd=None, name=None, noatime=False, op='op
     try:
         yield fd
     finally:
-        os.close(fd)
+        # On windows fd is None for directories.
+        if fd is not None:
+            os.close(fd)
 
 
 class DownloadPipeline:
diff --git a/src/borg/archiver.py b/src/borg/archiver.py
index 8fb6439d5..55ef22cde 100644
--- a/src/borg/archiver.py
+++ b/src/borg/archiver.py
@@ -625,8 +625,10 @@ class Archiver:
             elif stat.S_ISDIR(st.st_mode):
                 with OsOpen(path=path, parent_fd=parent_fd, name=name, flags=flags_dir,
                             noatime=True, op='dir_open') as child_fd:
-                    with backup_io('fstat'):
-                        st = stat_update_check(st, os.fstat(child_fd))
+                    # child_fd is None for directories on windows, in that case a race condition check is not possible.
+                    if child_fd is not None:
+                        with backup_io('fstat'):
+                            st = stat_update_check(st, os.fstat(child_fd))
                     if recurse:
                         tag_names = dir_is_tagged(path, exclude_caches, exclude_if_present)
                         if tag_names:
diff --git a/src/borg/helpers/fs.py b/src/borg/helpers/fs.py
index cb3f0ba8e..eecff277a 100644
--- a/src/borg/helpers/fs.py
+++ b/src/borg/helpers/fs.py
@@ -8,6 +8,7 @@ import sys
 import textwrap
 
 from .process import prepare_subprocess_env
+from ..platformflags import is_win32
 
 from ..constants import *  # NOQA
 
@@ -230,6 +231,9 @@ def os_open(*, flags, path=None, parent_fd=None, name=None, noatime=False):
         fname = name  # use name relative to parent_fd
     else:
         fname, parent_fd = path, None  # just use the path
+    if is_win32 and os.path.isdir(fname):
+        # Directories can not be opened on Windows.
+        return None
     _flags_normal = flags
     if noatime:
         _flags_noatime = _flags_normal | O_('NOATIME')