diff --git a/homeassistant/components/sensor/rainmachine.py b/homeassistant/components/sensor/rainmachine.py
index 5131b25510a..86a97bc291c 100644
--- a/homeassistant/components/sensor/rainmachine.py
+++ b/homeassistant/components/sensor/rainmachine.py
@@ -77,7 +77,7 @@ class RainMachineSensor(RainMachineEntity):
     async def async_added_to_hass(self):
         """Register callbacks."""
         @callback
-        def update(self):
+        def update():
             """Update the state."""
             self.async_schedule_update_ha_state(True)