diff --git a/keepassxc_browser/protocol.py b/keepassxc_browser/protocol.py
index b327d5c..1695144 100644
--- a/keepassxc_browser/protocol.py
+++ b/keepassxc_browser/protocol.py
@@ -257,6 +257,8 @@ def get_logins(self, identity, url, submit_url=None, http_auth=None):
     def set_login(
         self, identity, url, login=None, password=None, entry_id=None, submit_url=None
     ):
+        if not (url.startswith('mailto:') or url.startswith('https:') or url.startswith('vnc:')):
+            raise Exception('Url needs to start with "mailto:" or "https: or vnc:"')
         action = 'set-login'
         message = create_message(action, id=identity.associated_name, url=url)