diff --git a/scrapers/kattis.py b/scrapers/kattis.py
index 3ace5ba..fc80ff5 100644
--- a/scrapers/kattis.py
+++ b/scrapers/kattis.py
@@ -366,7 +366,7 @@ class KattisScraper(BaseScraper):
             except Exception as e:
                 return self._submit_error(f"Submit request failed: {e}")
 
-            if r.text == "Request validation failed":
+            if r.status_code in (400, 403) or r.text == "Request validation failed":
                 _COOKIE_PATH.unlink(missing_ok=True)
                 print(json.dumps({"status": "logging_in"}), flush=True)
                 ok = await _do_kattis_login(client, username, password)