diff --git a/flathunt.py b/flathunt.py
index 01880c6e..06683810 100644
--- a/flathunt.py
+++ b/flathunt.py
@@ -86,7 +86,7 @@ def launch_flat_hunt(config, heartbeat: Heartbeat):
             if config_handle is not None:
                 new_config = Config(filename=config_handle.name, silent=True)
 
-                if None in (config.last_modified_time, new_config.last_modified_time):
+                if config.last_modified_time is None or new_config.last_modified_time is None:
                     logger.warning("Could not compare last modification time of config file."
                                  "Keeping the old configuration")
                 elif config.last_modified_time < new_config.last_modified_time:
diff --git a/flathunter/config.py b/flathunter/config.py
index 34b2f43f..bc110a44 100644
--- a/flathunter/config.py
+++ b/flathunter/config.py
@@ -108,7 +108,12 @@ def __init__(self, config=None):
         self.config = config
         self.__searchers__ = []
         self.check_deprecated()
-        self.last_modified_time: Optional[float] = self.get_last_modified_time(self.config.get("filename"))
+        if filename := self.config.get("filename"):
+            self.last_modified_time: Optional[float] = self.get_last_modified_time(filename)
+        else:
+            self.last_modified_time: Optional[float] = None
+
+
 
     def __iter__(self):
         """Emulate dictionary"""