diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index 4da11b3..71a5828 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -38,6 +38,8 @@ static int __init start_kernel_proc(void *unused)
 	block_signals();
 	pid = os_getpid();
 
+	BUG_ON(pid == -516);
+
 	cpu_tasks[0].pid = pid;
 	cpu_tasks[0].task = current;
 #ifdef CONFIG_SMP
diff --git a/init/main.c b/init/main.c
index febc511..9ad68ab 100644
--- a/init/main.c
+++ b/init/main.c
@@ -386,6 +386,7 @@ static noinline void __init_refok rest_init(void)
 	kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
 	numa_default_policy();
 	pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
+	BUG_ON(pid == -516);
 	rcu_read_lock();
 	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
 	rcu_read_unlock();