diff --git a/script/keithley.py b/script/keithley.py
index 70b5e7ff..dc46b000 100644
--- a/script/keithley.py
+++ b/script/keithley.py
@@ -131,21 +131,20 @@ class Keithley(object):
         - float: current limit in A.
           values between 2e-11 and 2e-3 set a fixed range.
           values greater than 0.02 select AUTO.
-        - str: state label of EPICS channel (cf. self.RANGE_STATES)
-        - int: state index of EPICS channel
+        - str: state label of EPICS channel (cf. self.RANGE_STATES).
+          must be one of the state labels, otherwise a ValueError is raised.
+        - int: state index of EPICS channel (0...10)
         """
         if isinstance(value, float):
             try:
-                v = int(-math.log10(value / 2)) - 1
-                v = max(v, 0)
-                v = min(v, len(self.RANGE_STATES)-1)
+                value = int(-math.log10(value / 2)) - 1
+                value = max(value, 0)
+                value = min(value, len(self.RANGE_STATES)-1)
             except ValueError:
-                v = 0
-            print "set_range({fv}) -> set_range({iv})".format(fv=value, iv=v)
+                value = 0
         elif isinstance(value, str):
             value = self.RANGE_STATES.index(value)
         self.rangeCh.write(value)
-
         
 KeiSample = Keithley("SampleKeithley", "X03DA-KEITHLEY-1:")
 KeiReference = Keithley("ReferenceKeithley", "X03DA-KEITHLEY-2:")