diff --git a/calibrate.py b/calibrate.py
index a3a5f93..054df78 100644
--- a/calibrate.py
+++ b/calibrate.py
@@ -1,7 +1,7 @@
 from time import sleep
 import robot
 
-START_VALUES = (50, 50)
+START_VALUES = [50, 50]
 THRESHOLD = 1.01
 
 def test_forward(arlo, l_power, r_power):