diff --git a/background.go b/background.go
index 91635bf..e2e27eb 100644
--- a/background.go
+++ b/background.go
@@ -229,10 +229,13 @@ func (bg *Background) stop() {
 		return
 	}
 
+	// Note: The order of termination is important.
+	// Sender goroutines should be terminated before the receiver goroutines.
+	//
+	// processor -> syncer      (via syncRequestCh)
+	// processor -> heartbeater (via workerCh)
 	bg.scheduler.terminate()
 	bg.processor.terminate()
-	// Note: processor and all worker goroutines need to be exited
-	// before shutting down syncer to avoid goroutine leak.
 	bg.syncer.terminate()
 	bg.subscriber.terminate()
 	bg.heartbeater.terminate()
@@ -240,7 +243,6 @@ func (bg *Background) stop() {
 	bg.wg.Wait()
 
 	bg.rdb.Close()
-	bg.processor.handler = nil
 	bg.running = false
 
 	logger.info("Bye!")
diff --git a/subscriber_test.go b/subscriber_test.go
index 1a67159..0bc9258 100644
--- a/subscriber_test.go
+++ b/subscriber_test.go
@@ -27,8 +27,11 @@ func TestSubscriber(t *testing.T) {
 	}
 
 	for _, tc := range tests {
+		var mu sync.Mutex
 		called := false
 		fakeCancelFunc := func() {
+			mu.Lock()
+			defer mu.Unlock()
 			called = true
 		}
 		cancelations := base.NewCancelations()
@@ -46,6 +49,7 @@ func TestSubscriber(t *testing.T) {
 		// allow for redis to publish message
 		time.Sleep(time.Second)
 
+		mu.Lock()
 		if called != tc.wantCalled {
 			if tc.wantCalled {
 				t.Errorf("fakeCancelFunc was not called, want the function to be called")
@@ -53,6 +57,7 @@ func TestSubscriber(t *testing.T) {
 				t.Errorf("fakeCancelFunc was called, want the function to not be called")
 			}
 		}
+		mu.Unlock()
 
 		subscriber.terminate()
 	}