diff --git a/saqc/lib/ts_operators.py b/saqc/lib/ts_operators.py
index 669de2a0697339ac5f1f9cab686cb162ca061fdc..2d619ae4c63dfc01579d5664f8ab0a499803bef2 100644
--- a/saqc/lib/ts_operators.py
+++ b/saqc/lib/ts_operators.py
@@ -9,6 +9,8 @@
 """
 The module gathers all kinds of timeseries tranformations.
 """
+from __future__ import annotations
+
 import re
 import sys
 from typing import Literal, Union