diff --git a/src/seismic_hazard_forecasting.py b/src/seismic_hazard_forecasting.py
index 8b804d5..fc758ac 100644
--- a/src/seismic_hazard_forecasting.py
+++ b/src/seismic_hazard_forecasting.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from datetime import timedelta, datetime
+import numpy as np
 
 def datenum_to_datetime(datenum):
     # MATLAB epoch starts at year 0, Python's datetime starts at year 1