diff --git a/judge/judger/client.py b/judge/judger/client.py
index 5c305a3..6e171ea 100644
--- a/judge/judger/client.py
+++ b/judge/judger/client.py
@@ -63,7 +63,7 @@ class JudgeClient(object):
                   " --max-memory " + str(self._max_memory * 1000 * 1000) + \
                   " --network false" + \
                   " --syscalls '!execve:k,flock:k,ptrace:k,sync:k,fdatasync:k,fsync:k,msync,sync_file_range:k,syncfs:k" \
-                  ",unshare:k,setns:k,clone:k,query_module:k,sysinfo:k,syslog:k,sysfs:k'" + \
+                  ",unshare:k,setns:k,clone[a&268435456==268435456]:k,query_module:k,sysinfo:k,syslog:k,sysfs:k'" + \
                   " --uid " + str(lrun_uid) + \
                   " --gid " + str(lrun_gid)