diff --git a/r9/src/queue.rs b/r9/src/queue.rs
index 957c340..6811995 100644
--- a/r9/src/queue.rs
+++ b/r9/src/queue.rs
@@ -22,11 +22,11 @@ impl<T> Queue<T> {
         return this;
     }
 
-    pub fn push(&mut self, node: &Rc::<RefCell::<crate::ListHead<T>>>) {
+    pub fn push(&self, node: &Rc::<RefCell::<crate::ListHead<T>>>) {
         crate::ListHead::<T>::add_tail(&self.msg_list, node);
     }
 
-    pub fn fetch(&mut self) {
+    pub fn fetch(&self) {
         if !self.msg_list.borrow().empty() &&
             self.work_list.borrow().empty() {
                 crate::ListHead::replace_init(&self.work_list, &self.msg_list);