diff --git a/src/metar_navigate/utils/config_manager.py b/src/metar_navigate/utils/config_manager.py
index 5cdeb81..77344e9 100644
--- a/src/metar_navigate/utils/config_manager.py
+++ b/src/metar_navigate/utils/config_manager.py
@@ -22,7 +22,7 @@ class SingletonMeta(type):
 class ConfigManager(metaclass=SingletonMeta):
     def __init__(self):
         self.config_dir = DirectoryManager.get_config_directory()
-        self.__data = None
+        self.__data = dict()
 
     def read_config(self):
         if os.path.exists(f"{self.config_dir}/config.toml"):