diff --git a/scheme/env/command-level.scm b/scheme/env/command-level.scm
index 2dc7821..7de9875 100644
--- a/scheme/env/command-level.scm
+++ b/scheme/env/command-level.scm
@@ -299,7 +299,7 @@
     (for-each (lambda (thread)
 		(if (thread-continuation thread)
 		    (begin
-                      (remove-thread-from-queue! thread)
+                      (remove-thread-from-queues! thread)
 		      (interrupt-thread thread
 					(lambda ignore
 					  (terminate-current-thread)))
diff --git a/scheme/interfaces.scm b/scheme/interfaces.scm
index 73b859f..c7d7fa3 100644
--- a/scheme/interfaces.scm
+++ b/scheme/interfaces.scm
@@ -564,8 +564,9 @@
 	  make-thread-queue
 	  thread-queue-empty?
 	  enqueue-thread!
+	  multiple-enqueue-thread!
 	  dequeue-thread!
-	  remove-thread-from-queue!
+	  remove-thread-from-queues!
 
 	  event-pending?
 	  get-next-event!
diff --git a/scheme/rts/thread.scm b/scheme/rts/thread.scm
index dd77f38..2bb5ec7 100644
--- a/scheme/rts/thread.scm
+++ b/scheme/rts/thread.scm
@@ -42,7 +42,7 @@
   (really-make-thread dynamic-env dynamic-point
 		      cell-values own-cell-values?
 		      continuation scheduler
-		      queue arguments
+		      queues arguments
 		      events current-task uid name)
   thread?
   (dynamic-env    thread-dynamic-env)   ;Must be first!  (See fluid.scm)
@@ -54,7 +54,7 @@
 					;Must be fourth! (See thread-cell.scm)
   (own-cell-values? thread-own-cell-values? set-thread-own-values?!)
   (continuation   thread-continuation set-thread-continuation!)
-  (queue          thread-queue set-thread-queue!)
+  (queues         thread-queues set-thread-queues!)
   (arguments      thread-arguments set-thread-arguments!)
   (time           thread-time set-thread-time!)
   (scheduler      thread-scheduler set-thread-scheduler!)
@@ -173,22 +173,28 @@
 (define thread-queue-empty? queue-empty?)
 
 (define (enqueue-thread! queue thread)
-  (if (thread-queue thread)
+  (if (thread-queues thread)
       (error "enqueued thread being added to another queue" thread queue))
-  (set-thread-queue! thread queue)
+  (set-thread-queues! thread (list queue))
   (enqueue! queue thread))
 
+(define (multiple-enqueue-thread! queues thread)
+  (if (thread-queues thread)
+      (error "enqueued thread being added to another queue" thread queues))
+  (set-thread-queues! thread queues)
+  (for-each (lambda (q) (enqueue! q thread)) queues))
+
 (define (dequeue-thread! queue)
   (let ((thread (dequeue! queue)))
-    (set-thread-queue! thread #f)
+    (for-each (lambda (q) (delete-from-queue! q thread)) (thread-queues thread))
+    (set-thread-queues! thread #f)
     thread))
 
-(define (remove-thread-from-queue! thread)
-  (if (thread-queue thread)
+(define (remove-thread-from-queues! thread)
+  (if (thread-queues thread)
       (begin
-	(delete-from-queue! (thread-queue thread) thread)
-	(set-thread-queue! thread #f))))
-
+	(for-each (lambda (q) (delete-from-queue! q thread)) (thread-queues thread))
+	(set-thread-queues! thread #f))))
 ;----------------
 
 (define current-thread (structure-ref primitives current-thread))
@@ -239,8 +245,12 @@
 	  ((not (eq? (thread-scheduler thread) scheduler))
 	   (enable-interrupts!)
 	   (error "thread run by wrong scheduler" thread scheduler))
-	  ((thread-queue thread)
+	  ((thread-queues thread)
 	   (enable-interrupts!)
+	   (apply debug-message (list "thread run while still on a queue " 
+				      (thread-uid thread)
+				      (thread-name thread)
+				      (thread-queues thread)))
 	   (error "thread run while still on a queue" thread))
 	  ((and (thread-current-task thread)
 		(not (null? (thread-arguments thread))))
@@ -577,7 +587,7 @@
 ; Enqueue a RUNNABLE for THREAD's scheduler.
 
 (define (make-ready thread . args)
-  (if (thread-queue thread)
+  (if (thread-queues thread)
       (error "trying to schedule a queued thread" thread))
 ;  (if (not (null? (thread-arguments thread)))
 ;      (error "trying to replace thread arguments"))