diff --git a/cobaya/collection.py b/cobaya/collection.py
index 4d717a94..e0c5d11c 100644
--- a/cobaya/collection.py
+++ b/cobaya/collection.py
@@ -1181,7 +1181,6 @@ def _dump_slice__txt(self, n_min=None, n_max=None):
         with open(self.file_name, "a", encoding="utf-8") as out:
             np.savetxt(out, self.data[n_min:n_max].to_numpy(dtype=np.float64),
                        fmt=self._numpy_fmts)
-            os.fsync(out.fileno())
 
     def _delete__txt(self):
         try: