Index: kernel/generic/src/ipc/kbox.c
===================================================================
--- kernel/generic/src/ipc/kbox.c	(revision c96452180f7af3adf60e8b6f88ac2ad6ec1683e6)
+++ kernel/generic/src/ipc/kbox.c	(revision b060ca9420d7ad69e0ab5c89d34e86211a7f87df)
@@ -47,5 +47,4 @@
 void ipc_kbox_cleanup(void)
 {
-	ipl_t ipl;
 	bool have_kb_thread;
 
@@ -78,10 +77,8 @@
 	 * kbox thread to clean it up since sender != debugger.
 	 */
-	ipl = interrupts_disable();
-	spinlock_lock(&TASK->lock);
+	mutex_lock(&TASK->udebug.lock);
 	udebug_task_cleanup(TASK);
-	spinlock_unlock(&TASK->lock);
-	interrupts_restore(ipl);
-	
+	mutex_unlock(&TASK->udebug.lock);
+
 	if (have_kb_thread) {
 		LOG("Join kb.thread.");