diff --git a/src/seismic_hazard_forecasting.py b/src/seismic_hazard_forecasting.py
index 962516a..8b804d5 100644
--- a/src/seismic_hazard_forecasting.py
+++ b/src/seismic_hazard_forecasting.py
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+from datetime import timedelta, datetime
+
 def datenum_to_datetime(datenum):
     # MATLAB epoch starts at year 0, Python's datetime starts at year 1
     matlab_epoch = datetime(1, 1, 1)