diff --git a/launcher.go b/launcher.go
index 146982d..02e3b7e 100644
--- a/launcher.go
+++ b/launcher.go
@@ -54,6 +54,7 @@ func (l *Launcher) Stop() {
 		return
 	}
 	l.running = false
+	l.processor.handler = nil
 
 	l.poller.terminate()
 	l.processor.terminate()
diff --git a/poller.go b/poller.go
index 7569278..3d09eb0 100644
--- a/poller.go
+++ b/poller.go
@@ -36,6 +36,7 @@ func (p *poller) terminate() {
 	p.done <- struct{}{}
 }
 
+// start starts the "poller" goroutine.
 func (p *poller) start() {
 	go func() {
 		for {
@@ -65,6 +66,7 @@ func (p *poller) exec() {
 		fmt.Printf("[DEBUG] got %d tasks from %q\n", len(msgs), zset)
 
 		for _, m := range msgs {
+			// TODO(hibiken): Make this move operation atomic.
 			if err := p.rdb.move(zset, m); err != nil {
 				log.Printf("could not move task %+v to queue %q: %v", m, m.Queue, err)
 				continue
diff --git a/processor.go b/processor.go
index aba4968..e2330a0 100644
--- a/processor.go
+++ b/processor.go
@@ -29,7 +29,7 @@ func newProcessor(rdb *rdb, numWorkers int, handler TaskHandler) *processor {
 }
 
 func (p *processor) terminate() {
-	// Signal he processor goroutine to stop processing tasks from the queue.
+	// Signal the processor goroutine to stop processing tasks from the queue.
 	p.done <- struct{}{}
 
 	fmt.Println("--- Waiting for all workers to finish ---")
@@ -57,10 +57,11 @@ func (p *processor) start() {
 }
 
 func (p *processor) exec() {
-	// pull message out of the queue and process it
+	const timeout = 5 * time.Second
+	// pull a task out of the queue and process it
 	// TODO(hibiken): sort the list of queues in order of priority
 	// NOTE: BLPOP needs to timeout in case a new queue is added.
-	msg, err := p.rdb.bpop(5*time.Second, p.rdb.listQueues()...)
+	msg, err := p.rdb.bpop(timeout, p.rdb.listQueues()...)
 	if err != nil {
 		switch err {
 		case errQueuePopTimeout: