diff --git a/src/borg/archive.py b/src/borg/archive.py
index ef5de3f0c..f9fdfc129 100644
--- a/src/borg/archive.py
+++ b/src/borg/archive.py
@@ -834,6 +834,7 @@ Utilization of max. archive size: {csize_max:.0%}
                 with backup_io('open'):
                     fd = open(path, 'wb')
                 with fd:
+                    trailing_hole = False
                     ids = [c.id for c in item.chunks]
                     for data in self.pipeline.fetch_many(ids, is_preloaded=True):
                         if pi:
@@ -842,10 +843,18 @@ Utilization of max. archive size: {csize_max:.0%}
                             if sparse and zeros.startswith(data):
                                 # all-zero chunk: create a hole in a sparse file
                                 fd.seek(len(data), 1)
+                                trailing_hole = True
                             else:
                                 fd.write(data)
+                                trailing_hole = False
                     with backup_io('truncate_and_attrs'):
                         pos = item_chunks_size = fd.tell()
+                        if is_win32 and trailing_hole and pos > 0:
+                            # Windows: truncate() does not zero-fill properly (no VDL update).
+                            # Writing a single zero at the end forces NTFS to zero-fill the hole
+                            # and update valid data length.
+                            fd.seek(pos - 1)
+                            fd.write(b"\0")
                         fd.truncate(pos)
                         fd.flush()
                         self.restore_attrs(path, item, fd=fd.fileno())