diff --git a/src/greedy_packer.rs b/src/greedy_packer.rs
index d31fa08..4e7d271 100644
--- a/src/greedy_packer.rs
+++ b/src/greedy_packer.rs
@@ -1,14 +1,18 @@
 use crate::lz;
 use crate::match_finder::MatchFinder;
 use crate::rans::RansCoder;
+use crate::ProgressCallback;
 
-pub fn pack(data: &[u8]) -> Vec<u8> {
+pub fn pack(data: &[u8], mut progress_callback: Option<ProgressCallback>) -> Vec<u8> {
     let mut match_finder = MatchFinder::new(data);
     let mut rans_coder = RansCoder::new();
     let mut state = lz::CoderState::new();
 
     let mut pos = 0;
     while pos < data.len() {
+        if let Some(ref mut cb) = progress_callback {
+            cb(pos);
+        }
         let mut encoded_match = false;
         if let Some(m) = match_finder.matches(pos).next() {
             let max_offset = 1 << (m.length * 3 - 1).min(31);
diff --git a/src/lib.rs b/src/lib.rs
index b8db242..d5153b8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,8 +5,14 @@ mod match_finder;
 mod rans;
 mod parsing_packer;
 
-pub use greedy_packer::pack as pack_fast;
-pub use parsing_packer::pack;
 pub use lz::unpack;
 
-pub type ProgressCallback<'a> = &'a mut dyn FnMut(usize);
\ No newline at end of file
+pub type ProgressCallback<'a> = &'a mut dyn FnMut(usize);
+
+pub fn pack(data: &[u8], level: u8, progress_callback: Option<ProgressCallback>) -> Vec<u8> {
+    if level == 0 {
+        greedy_packer::pack(data, progress_callback)
+    } else {
+        parsing_packer::pack(data, level, progress_callback)
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index bba8243..4a669bb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,21 +15,18 @@ fn main() -> Result<()> {
 
             let mut data = vec![];
             File::open(infile)?.read_to_end(&mut data)?;
-            let packed_data = if level == 0 {
-                upkr::pack_fast(&data)
-            } else {
-                let mut pb = pbr::ProgressBar::new(data.len() as u64);
-                pb.set_units(pbr::Units::Bytes);
-                let packed_data = upkr::pack(
-                    &data,
-                    level,
-                    Some(&mut |pos| {
-                        pb.set(pos as u64);
-                    }),
-                );
-                pb.finish();
-                packed_data
-            };
+            
+            let mut pb = pbr::ProgressBar::new(data.len() as u64);
+            pb.set_units(pbr::Units::Bytes);
+            let packed_data = upkr::pack(
+                &data,
+                level,
+                Some(&mut |pos| {
+                    pb.set(pos as u64);
+                }),
+            );
+            pb.finish();
+
             println!(
                 "Compressed {} bytes to {} bytes ({}%)",
                 data.len(),
@@ -57,7 +54,7 @@ fn main() -> Result<()> {
 
 fn print_help() {
     eprintln!("Usage:");
-    eprintln!("  upkr pack <infile> <outfile>");
+    eprintln!("  upkr pack [-l level(0-9)] <infile> <outfile>");
     eprintln!("  upkr unpack <infile> <outfile>");
     std::process::exit(1);
 }