diff --git a/src/listhead.rs b/src/listhead.rs
index d2e4426..e1c3802 100644
--- a/src/listhead.rs
+++ b/src/listhead.rs
@@ -60,8 +60,8 @@ impl<T> ListHead<T> {
         return self as *const ListHead<T> == self.next.upgrade().unwrap().as_ptr();
     }
 
-    pub fn add_tail(head: &mut Rc::<RefCell::<ListHead<T>>>,
-                    pnew: &mut Rc::<RefCell::<ListHead<T>>>) {
+    pub fn add_tail(head: &Rc::<RefCell::<ListHead<T>>>,
+                    pnew: &Rc::<RefCell::<ListHead<T>>>) {
         let prev = &mut head.borrow_mut().prev;
         let next = Rc::downgrade(head);
 
diff --git a/src/timer.rs b/src/timer.rs
index da09b94..ea3b881 100644
--- a/src/timer.rs
+++ b/src/timer.rs
@@ -13,7 +13,7 @@ const TVR_MASK: usize = TVR_SIZE - 1;
 pub type TimerWp = Weak::<Rc::<RefCell::<TimerList>>>;
 
 pub struct TimerAttacher {
-    timers: Rc::<RefCell::<crate::ListHead<TimerAttacher>>>,
+    timers: Rc::<RefCell::<crate::ListHead<TimerList>>>,
 }
 
 enum TimerType {
@@ -132,7 +132,8 @@ impl Timer {
         t.borrow_mut().expires = (self.get_tick_count)() + expire_time as i64;
         match attacher {
             Some(v) => {
-
+                crate::ListHead::add_tail(&v.borrow_mut().timers,
+                                          &t.borrow_mut().attach_entry);
             }
             None => {