diff --git a/homeassistant/components/simplisafe/__init__.py b/homeassistant/components/simplisafe/__init__.py
index 4895d43b162..37fa1761c6b 100644
--- a/homeassistant/components/simplisafe/__init__.py
+++ b/homeassistant/components/simplisafe/__init__.py
@@ -450,7 +450,7 @@ class SimpliSafe:
         """Initialize the data class."""
         asyncio.create_task(self.websocket.async_connect())
         self._hass.bus.async_listen_once(
-            EVENT_HOMEASSISTANT_STOP, self.websocket.async_disconnect
+            EVENT_HOMEASSISTANT_STOP, self.websocket.async_disconnect()
         )
 
         self.systems = await self._api.get_systems()