diff --git a/pcmdi_metrics/precip_variability/variability_across_timescales_PS_driver.py b/pcmdi_metrics/precip_variability/variability_across_timescales_PS_driver.py
index a0d9ce42e..b17fd05bf 100644
--- a/pcmdi_metrics/precip_variability/variability_across_timescales_PS_driver.py
+++ b/pcmdi_metrics/precip_variability/variability_across_timescales_PS_driver.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python
+
 import copy
 import glob
 import os