diff --git a/controller/state/changer.py b/controller/state/changer.py
index 687f6ae..45e3e5f 100644
--- a/controller/state/changer.py
+++ b/controller/state/changer.py
@@ -24,11 +24,11 @@ class Changer(object):
             change()
         return self.local_state
 
-    def open_valve():
+    def open_valve(self):
         GPIO.output(config.GPIO_PIN_VALVE, GPIO.HIGH)
         self.local_state['out_valve'] = 'open'
 
-    def close_valve():
+    def close_valve(self):
         GPIO.output(config.GPIO_PIN_VALVE, GPIO.LOW)
         self.local_state['out_valve'] = 'closed'