diff --git a/copyparty/cfg.py b/copyparty/cfg.py
index 10e921e8..abfb6c13 100644
--- a/copyparty/cfg.py
+++ b/copyparty/cfg.py
@@ -116,6 +116,7 @@ flagcats = {
         "hardlink": "does dedup with hardlinks instead of symlinks",
         "neversymlink": "disables symlink fallback; full copy instead",
         "copydupes": "disables dedup, always saves full copies of dupes",
+        "sparse": "force use of sparse files, mainly for s3-backed storage",
         "daw": "enable full WebDAV write support (dangerous);\nPUT-operations will now \033[1;31mOVERWRITE\033[0;35m existing files",
         "nosub": "forces all uploads into the top folder of the vfs",
         "magic": "enables filetype detection for nameless uploads",
diff --git a/copyparty/up2k.py b/copyparty/up2k.py
index 9abcfd7a..372d0c6a 100644
--- a/copyparty/up2k.py
+++ b/copyparty/up2k.py
@@ -3956,7 +3956,13 @@ class Up2k(object):
 
             if not ANYWIN and sprs and sz > 1024 * 1024:
                 fs = self.fstab.get(pdir)
-                if fs != "ok":
+                if fs == "ok":
+                    pass
+                elif "sparse" in self.flags[job["ptop"]]:
+                    t = "volflag 'sparse' is forcing use of sparse files for uploads to [%s]"
+                    self.log(t % (job["ptop"],))
+                    relabel = True
+                else:
                     relabel = True
                     f.seek(1024 * 1024 - 1)
                     f.write(b"e")