diff --git a/law/contrib/mattermost/notification.py b/law/contrib/mattermost/notification.py
index 48acf55d..5f580101 100644
--- a/law/contrib/mattermost/notification.py
+++ b/law/contrib/mattermost/notification.py
@@ -41,17 +41,17 @@ def notify_mattermost(
 
     # get default settings
     if not hook_url:
-        hook_url = cfg.get_expanded("notifications", "mattermost_hook_url")
+        hook_url = cfg.get_expanded("notifications", "mattermost_hook_url", default=None)
     if not channel:
-        channel = cfg.get_expanded("notifications", "mattermost_channel")
+        channel = cfg.get_expanded("notifications", "mattermost_channel", default=None)
     if not user:
-        user = cfg.get_expanded("notifications", "mattermost_user")
+        user = cfg.get_expanded("notifications", "mattermost_user", default=None)
     if not mention_user:
-        mention_user = cfg.get_expanded("notifications", "mattermost_mention_user")
+        mention_user = cfg.get_expanded("notifications", "mattermost_mention_user", default=None)
     if not icon_url:
-        icon_url = cfg.get_expanded("notifications", "mattermost_icon_url")
+        icon_url = cfg.get_expanded("notifications", "mattermost_icon_url", default=None)
     if not icon_emoji:
-        icon_emoji = cfg.get_expanded("notifications", "mattermost_icon_emoji")
+        icon_emoji = cfg.get_expanded("notifications", "mattermost_icon_emoji", default=None)
 
     if not hook_url:
         logger.warning(f"cannot send Mattermost notification, hook_url ({hook_url}) empty")
diff --git a/law/contrib/mattermost/parameter.py b/law/contrib/mattermost/parameter.py
index 428893a5..e1b07fc7 100644
--- a/law/contrib/mattermost/parameter.py
+++ b/law/contrib/mattermost/parameter.py
@@ -34,7 +34,7 @@ def notify(cls, success: bool, title: str, content: dict[str, Any], **kwargs) ->
 
         # overwrite title
         cfg = Config.instance()
-        header = cfg.get_expanded("notifications", "mattermost_header")
+        header = cfg.get_expanded("notifications", "mattermost_header", default=None)
         task_block = f"```\n{content['Task']}\n```"
         title = f"{header}\n{task_block}" if header else task_block
         del content["Task"]
@@ -46,7 +46,11 @@ def notify(cls, success: bool, title: str, content: dict[str, Any], **kwargs) ->
         # prepend the status text to the message content
         cfg = Config.instance()
         status_text = "success" if success else "failure"
-        status_emoji = cfg.get_expanded("notifications", f"mattermost_{status_text}_emoji")
+        status_emoji = cfg.get_expanded(
+            "notifications",
+            f"mattermost_{status_text}_emoji",
+            default=None,
+        )
         if status_emoji:
             status_text += " " + status_emoji
         content["Status"] = status_text