diff --git a/homeassistant/components/fritz/common.py b/homeassistant/components/fritz/common.py
index f05fea0dcd4..1958dd51f38 100644
--- a/homeassistant/components/fritz/common.py
+++ b/homeassistant/components/fritz/common.py
@@ -135,7 +135,7 @@ class FritzBoxTools:
         """Retrieve latest information from the FRITZ!Box."""
         return self.fritzhosts.get_hosts_info()
 
-    def scan_devices(self, now: datetime | None) -> None:
+    def scan_devices(self, now: datetime | None = None) -> None:
         """Scan for new devices and return a list of found device ids."""
         _LOGGER.debug("Checking devices for FRITZ!Box router %s", self.host)