diff --git a/extensions/fablabchemnitz/laser_check/laser_check.py b/extensions/fablabchemnitz/laser_check/laser_check.py
index 075fce80..d6999ae7 100644
--- a/extensions/fablabchemnitz/laser_check/laser_check.py
+++ b/extensions/fablabchemnitz/laser_check/laser_check.py
@@ -5,6 +5,7 @@ from inkex.bezier import csplength, csparea
 from lxml import etree
 import re
 import math
+import sys
 from math import log
 import datetime