diff --git a/src/pyoncatqt/login.py b/src/pyoncatqt/login.py
index ccfae09..9ac4dac 100644
--- a/src/pyoncatqt/login.py
+++ b/src/pyoncatqt/login.py
@@ -221,8 +221,11 @@ def __init__(
         # OnCat agent
 
         self.oncat_url = get_data("login.oncat", "oncat_url")
-        self.client_id = client_id or get_data("login.oncat", f"{key}_id")
-        if not self.client_id:
+        if client_id is not None:
+            self.client_id = client_id
+        elif key is not None:
+            self.client_id = get_data("login.oncat", f"{key}_id")
+        else:
             raise ValueError(f"Invalid module {key}. No OnCat client Id is found or provided for this application.")
 
         # use the partial client id to generate the filename
@@ -252,8 +255,6 @@ def update_connection_status(self: QGroupBox) -> None:
             self.status_label.setText("ONCat: Disconnected")
             self.status_label.setStyleSheet("color: red")
 
-        # self.connection_updated.emit(self.is_connected)
-
     @property
     def is_connected(self: QGroupBox) -> bool:
         """