diff --git a/mongo/submission.py b/mongo/submission.py
index fb972fd..953ab1d 100644
--- a/mongo/submission.py
+++ b/mongo/submission.py
@@ -487,7 +487,7 @@ def process_result(self, tasks: list):
             # save stdout/stderr
             fds = ['stdout', 'stderr']
             for j, case in enumerate(cases):
-                tf = NamedTemporaryFile(delete=False)
+                tf = NamedTemporaryFile(delete=True)
                 with ZipFile(tf, 'w') as zf:
                     for fd in fds:
                         content = case.pop(fd)