diff --git a/views/problem.ejs b/views/problem.ejs
index 8bafbb6..4153a0e 100644
--- a/views/problem.ejs
+++ b/views/problem.ejs
@@ -222,11 +222,9 @@ div[class*=ace_br] {
<%
- let formUrl;
- if (contest) formUrl = syzoj.utils.makeUrl(['problem', problem.id, 'submit'], { contest_id: contest.id });
- else formUrl = syzoj.utils.makeUrl(['problem', problem.id, 'submit']);
+ const formUrl = syzoj.utils.makeUrl(['problem', problem.id, 'submit'], { contest_id: contest ? contest.id : undefined, _csrf: req.csrfToken() });
%>
-