diff --git a/controller/sensors.py b/controller/sensors.py
index 13e0082..2981731 100644
--- a/controller/sensors.py
+++ b/controller/sensors.py
@@ -11,7 +11,7 @@ GPIO.setup(config.GPIO_PIN_TANKFULL, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
 
 # tank sensor has inverse logic - 0 when it is full 1 when it is not
 # so we are inverting its value here
-tankFull = !GPIO.input(config.GPIO_PIN_TANKFULL)
+tankFull = (not GPIO.input(config.GPIO_PIN_TANKFULL))
 GPIO.cleanup()
 print 'Bacva puna: {}'.format(tankFull)