diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 03923a138ef5..9b38f94b5dd0 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -1660,7 +1660,8 @@ static void tomoyo_read_pid(struct tomoyo_io_buffer *head)
 	head->r.eof = true;
 	if (tomoyo_str_starts(&buf, "global-pid "))
 		global_pid = true;
-	pid = (unsigned int) simple_strtoul(buf, NULL, 10);
+	if (kstrtouint(buf, 10, &pid))
+		return;
 	rcu_read_lock();
 	if (global_pid)
 		p = find_task_by_pid_ns(pid, &init_pid_ns);