diff --git a/homeassistant/components/zwave_js/config_flow.py b/homeassistant/components/zwave_js/config_flow.py
index c5831fe9dc1..7733e0325ec 100644
--- a/homeassistant/components/zwave_js/config_flow.py
+++ b/homeassistant/components/zwave_js/config_flow.py
@@ -347,7 +347,6 @@ class ZWaveJSConfigFlow(BaseZwaveJSFlow, ConfigFlow, domain=DOMAIN):
     VERSION = 1
 
     _title: str
-    unique_id: str
 
     def __init__(self) -> None:
         """Set up flow instance."""
@@ -396,6 +395,7 @@ class ZWaveJSConfigFlow(BaseZwaveJSFlow, ConfigFlow, domain=DOMAIN):
             return await self.async_step_manual({CONF_URL: self.ws_address})
 
         assert self.ws_address
+        assert self.unique_id
         return self.async_show_form(
             step_id="zeroconf_confirm",
             description_placeholders={