diff --git a/rdc_TRES.py b/rdc_TRES.py
index a71b1b2..c40a52d 100644
--- a/rdc_TRES.py
+++ b/rdc_TRES.py
@@ -3,7 +3,8 @@
 from amuse.io import read_set_from_file
 from amuse.support.console import set_printing_strategy
 import numpy as np
-import io
+import io
+import sys
     
 minimum_time_step = 1.e-9 |units.Myr