diff --git a/src/cpl/configuration/configuration.py b/src/cpl/configuration/configuration.py
index 55e35a4f..1a3472a3 100644
--- a/src/cpl/configuration/configuration.py
+++ b/src/cpl/configuration/configuration.py
@@ -334,7 +334,7 @@ class Configuration(ConfigurationABC):
             self._print_error(__name__, f'Cannot load config file: {file}! -> {e}')
             return {}
 
-    def add_configuration(self, key_type: type, value: ConfigurationModelABC):
+    def add_configuration(self, key_type: Union[str, type], value: ConfigurationModelABC):
         self._config[key_type] = value
 
     def get_configuration(self, search_type: Union[str, Type[ConfigurationModelABC]]) -> Union[
diff --git a/src/cpl/configuration/configuration_abc.py b/src/cpl/configuration/configuration_abc.py
index 2fc03bb5..0d0e7ed7 100644
--- a/src/cpl/configuration/configuration_abc.py
+++ b/src/cpl/configuration/configuration_abc.py
@@ -72,7 +72,7 @@ class ConfigurationABC(ABC):
         pass
 
     @abstractmethod
-    def add_configuration(self, key_type: type, value: object):
+    def add_configuration(self, key_type: Union[str, type], value: object):
         """
         Add configuration object
         :param key_type: