diff --git a/src/nqrduck_spectrometer/pulseparameters.py b/src/nqrduck_spectrometer/pulseparameters.py
index 72d41a3..260dbb5 100644
--- a/src/nqrduck_spectrometer/pulseparameters.py
+++ b/src/nqrduck_spectrometer/pulseparameters.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import logging
 import numpy as np
 import sympy