diff --git a/Controll.py b/Controll.py
index ccc4b01..86bf640 100644
--- a/Controll.py
+++ b/Controll.py
@@ -10,8 +10,8 @@ sess.add_all()
 controllers = {dev.serial: DeviceController(dev) for dev in sess.devices}
 serials = list(controllers.keys())
 
-for i in enumerate(serials):
-    c = controllers[i]
+for i, serial in enumerate(serials):
+    c = controllers[serial]
     c.set_mode(0, pysmu.Mode.SIMV)  # CH A Hi-Z
     c.set_mode(1, pysmu.Mode.HI_Z)  # CH B Hi-Z
     MainWindow.add_list_item(MainWindow, serials[i], i, c.start, c.stop)