diff --git a/homeassistant/components/rachio/switch.py b/homeassistant/components/rachio/switch.py
index 2b9a959deb2c9e5fd09039c35f84cc9a1eaaee8b..764f87e924c40a77e733ea2bc1361878c8fed925 100644
--- a/homeassistant/components/rachio/switch.py
+++ b/homeassistant/components/rachio/switch.py
@@ -192,7 +192,7 @@ class RachioZone(RachioSwitch):
         self._person = person
         self._shade_type = data.get(KEY_CUSTOM_SHADE, {}).get(KEY_NAME)
         self._zone_type = data.get(KEY_CUSTOM_CROP, {}).get(KEY_NAME)
-        self._summary = str()
+        self._summary = ""
         self._current_schedule = current_schedule
         super().__init__(controller, poll=False)
         self._state = self.zone_id == self._current_schedule.get(KEY_ZONE_ID)
@@ -275,7 +275,7 @@ class RachioZone(RachioSwitch):
         if args[0][KEY_ZONE_ID] != self.zone_id:
             return
 
-        self._summary = kwargs.get(KEY_SUMMARY, str())
+        self._summary = kwargs.get(KEY_SUMMARY, "")
 
         if args[0][KEY_SUBTYPE] == SUBTYPE_ZONE_STARTED:
             self._state = True
diff --git a/homeassistant/components/rachio/webhooks.py b/homeassistant/components/rachio/webhooks.py
index 7051ec046d84ec1934cf517d20f55d69b4bc8c83..e31b32e9410fd68ffe87a762c9479ba1119b71a7 100644
--- a/homeassistant/components/rachio/webhooks.py
+++ b/homeassistant/components/rachio/webhooks.py
@@ -88,7 +88,7 @@ class RachioWebhookView(HomeAssistantView):
         data = await request.json()
 
         try:
-            auth = data.get(KEY_EXTERNAL_ID, str()).split(":")[1]
+            auth = data.get(KEY_EXTERNAL_ID, "").split(":")[1]
             assert auth == hass.data[DOMAIN][self._entry_id].rachio.webhook_auth
         except (AssertionError, IndexError):
             return web.Response(status=web.HTTPForbidden.status_code)
diff --git a/homeassistant/components/zwave/config_flow.py b/homeassistant/components/zwave/config_flow.py
index 6d7dc012e859cbb84f94376935e25eaefd34ab85..cff197b7e97813acd9dac84ea503b2f14f266b0b 100644
--- a/homeassistant/components/zwave/config_flow.py
+++ b/homeassistant/components/zwave/config_flow.py
@@ -66,7 +66,7 @@ class ZwaveFlowHandler(config_entries.ConfigFlow):
                 # Generate a random key
                 from random import choice
 
-                key = str()
+                key = ""
                 for i in range(16):
                     key += "0x"
                     key += choice("1234567890ABCDEF")