diff --git a/src/lib.rs b/src/lib.rs
index a3516a5..09eb620 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 extern crate term;
 
 use std::{
+    cell::RefCell,
     env,
     fs,
     io::{self, Write, Error, ErrorKind},
@@ -240,12 +241,11 @@ pub fn extract_package_and_wait(dir: &str, file_name: &str) -> io::Result<()> {
 
 pub fn copy_io<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W, total: i64) -> io::Result<u64>
         where R: io::Read, W: io::Write {
-    // let mut written = 0u64;
-    // let written_cell = RefCell::new(written);
+    let written_cell = RefCell::new(0u64);
     let start = SystemTime::now();
-    let written = copy_io_callback(reader, writer, total, &|total, written, _len| {
-       // let mut written_borrowed = written_cell.borrow_mut();
-        //written_cell.replace_with(|&mut old_written| old_written + len as u64);
+    let written = copy_io_callback(reader, writer, total, &|total, _written, len| {
+        written_cell.replace_with(|&mut w| w + len as u64);
+        let written = *written_cell.borrow();
         let cost = SystemTime::now().duration_since(start.clone()).unwrap().as_secs();
         let mut download_speed = "-".to_string();
         if cost > 0 {