-file_sync_after_first=$(mktemp --tmpdir -u tmp.test_nprocesses_sync_after_first.XXXXXX)
-file_sync_before_last=$(mktemp --tmpdir -u tmp.test_nprocesses_sync_before_last.XXXXXX)
+file_sync_after_first=$(mktemp -u -t tmp.test_nprocesses_sync_after_first.XXXXXX)
+file_sync_before_last=$(mktemp -u -t tmp.test_nprocesses_sync_before_last.XXXXXX)