diff --git a/moo/kernel/System.moo b/moo/kernel/System.moo
index af6db13..39196b0 100644
--- a/moo/kernel/System.moo
+++ b/moo/kernel/System.moo
@@ -172,7 +172,7 @@ class System(Apex)
 /* TODO: end redo */
 
 			caller terminate.
-			//(Processor _processById: 1) resume. <---- i shouldn't do ths. but, this system causes VM assertion failure. fix it....
+			(Processor _processById: 1) resume. //<---- i shouldn't do ths. but, this system causes VM assertion failure. fix it....
 
 			System logNl: '>>>>End of OS signal handler process ' & (thisProcess id) asString.
 		].
diff --git a/moo/lib/exec.c b/moo/lib/exec.c
index 9ee4d0d..331d462 100644
--- a/moo/lib/exec.c
+++ b/moo/lib/exec.c
@@ -537,6 +537,8 @@ static MOO_INLINE void chain_into_semaphore (moo_t* moo, moo_oop_process_t proc,
 	/* a process chained to a semaphore cannot get chained to
 	 * a semaphore again. a process can get chained to a single semaphore 
 	 * or a single semaphore group only */
+	if ((moo_oop_t)proc->sem != moo->_nil) return; /* ignore it if it happens anyway. TODO: is it desirable???? */
+
 	MOO_ASSERT (moo, (moo_oop_t)proc->sem == moo->_nil);
 	MOO_ASSERT (moo, (moo_oop_t)proc->sem_wait.prev == moo->_nil);
 	MOO_ASSERT (moo, (moo_oop_t)proc->sem_wait.next == moo->_nil);