diff --git a/zfs-backup.py b/zfs-backup.py
index 6908ed2..1df4d7c 100755
--- a/zfs-backup.py
+++ b/zfs-backup.py
@@ -439,9 +439,7 @@ class Dataset:
             self._clean_old_snapshots_for_interval(interval, number)
 
     def _clean_old_snapshots_for_interval(self, interval: str, max_count: int):
-        regex = _get_regex_matching_snapshots_with_tags(
-            [config.snapshot_tag, interval]
-        )
+        regex = _get_regex_matching_snapshots_with_tags([config.snapshot_tag, interval])
         snapshots = [
             snapshot for snapshot in self.snapshots if snapshot.matches_regex(regex)
         ]