Index: kernel/generic/src/proc/scheduler.c
===================================================================
--- kernel/generic/src/proc/scheduler.c	(revision da1bafb8cf9a3b3be8ef21bc114daaa476a85190)
+++ kernel/generic/src/proc/scheduler.c	(revision 6cb8dba0db19a0ab69da1cae8e595d900987c579)
@@ -379,6 +379,4 @@
  * switch to a new thread.
  *
- * Assume THREAD->lock is held.
- *
  */
 void scheduler_separated_stack(void)
@@ -388,4 +386,5 @@
 	as_t *old_as = AS;
 	
+	ASSERT(!THREAD || irq_spinlock_locked(&THREAD->lock));
 	ASSERT(CPU != NULL);