diff --git a/src/listhead.rs b/src/listhead.rs
index 6ceccc5..a322303 100644
--- a/src/listhead.rs
+++ b/src/listhead.rs
@@ -77,7 +77,7 @@ impl<T> ListHead<T> {
         return self.next.upgrade().unwrap().borrow().data();
     }
 
-    pub fn replace_init(head: &mut Rc::<RefCell::<ListHead<T>>>,
+    pub fn replace_init(head: &Rc::<RefCell::<ListHead<T>>>,
                         pnew: &mut Rc::<RefCell::<ListHead<T>>>) {
         pnew.borrow_mut().next = head.borrow_mut().next.clone();
         pnew.borrow_mut().next.upgrade().unwrap().borrow_mut().prev = Rc::downgrade(pnew);
diff --git a/src/timer.rs b/src/timer.rs
index 61c9d6b..c2853f9 100644
--- a/src/timer.rs
+++ b/src/timer.rs
@@ -167,7 +167,26 @@ impl Timer {
         return p;
     }
 
-    fn cascade(&mut self, tv: &mut [TimerListListHeadRp], index: usize) -> usize {
+    fn cascade(&mut self, idx: usize) -> usize {
+        let index = self.get_timer_index(idx);
+        let tv : &mut [TimerListListHeadRp];
+        match idx {
+            0 => {
+                tv = &mut self.tv2;
+            }
+            1 => {
+                tv = &mut self.tv3;
+            }
+            2 => {
+                tv = &mut self.tv4;
+            }
+            3 => {
+                tv = &mut self.tv5;
+            }
+            _ => {
+                tv = &mut self.tv5;
+            }
+        }
         if !tv[index].borrow().empty() {
             let mut cascade_list = crate::ListHead::<TimerList>::new_head();
             crate::ListHead::<TimerList>::replace_init
@@ -194,7 +213,10 @@ impl Timer {
         while tick >= self.timer_tick {
             let index = (self.timer_tick & (TVR_MASK as i64)) as usize;
             if index == 0 &&
-                self.cascade(&mut self.tv2, self.get_timer_index(0)) == 0 {
+                self.cascade(0) == 0 &&
+                self.cascade(1) == 0 &&
+                self.cascade(2) == 0 {
+                    self.cascade(3);
             }
             self.timer_tick += 1;