diff --git a/src/main.rs b/src/main.rs
index 2f49d58..3f84e41 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,6 +14,7 @@ fn main() -> Result<()> {
             let parity_contexts = args
                 .opt_value_from_str(["-p", "--parity"])?
                 .unwrap_or(1usize);
+            let reverse = args.contains(["-r", "--reverse"]);
 
             if parity_contexts != 1 && parity_contexts != 2 && parity_contexts != 4 {
                 eprintln!("--parity has to be 1, 2 or 4");
@@ -25,10 +26,13 @@ fn main() -> Result<()> {
 
             let mut data = vec![];
             File::open(infile)?.read_to_end(&mut data)?;
+            if reverse {
+                data.reverse();
+            }
 
             let mut pb = pbr::ProgressBar::new(data.len() as u64);
             pb.set_units(pbr::Units::Bytes);
-            let packed_data = upkr::pack(
+            let mut packed_data = upkr::pack(
                 &data,
                 level,
                 use_bitstream,
@@ -39,6 +43,10 @@ fn main() -> Result<()> {
             );
             pb.finish();
 
+            if reverse {
+                packed_data.reverse();
+            }
+
             println!(
                 "Compressed {} bytes to {} bytes ({}%)",
                 data.len(),
@@ -52,6 +60,7 @@ fn main() -> Result<()> {
             let parity_contexts = args
                 .opt_value_from_str(["-p", "--parity"])?
                 .unwrap_or(1usize);
+            let reverse = args.contains(["-r", "--reverse"]);
 
             if parity_contexts != 1 && parity_contexts != 2 && parity_contexts != 4 {
                 eprintln!("--parity has to be 1, 2 or 4");
@@ -63,8 +72,14 @@ fn main() -> Result<()> {
 
             let mut data = vec![];
             File::open(infile)?.read_to_end(&mut data)?;
-            let packed_data = upkr::unpack(&data, use_bitstream, parity_contexts);
-            File::create(outfile)?.write_all(&packed_data)?;
+            if reverse {
+                data.reverse();
+            }
+            let mut unpacked_data = upkr::unpack(&data, use_bitstream, parity_contexts);
+            if reverse {
+                unpacked_data.reverse();
+            }
+            File::create(outfile)?.write_all(&unpacked_data)?;
         }
         Some(other) => {
             bail!("Unknown subcommand '{}'", other);
@@ -82,5 +97,6 @@ fn print_help() {
     eprintln!(" -b, --bitstream     bitstream mode");
     eprintln!(" -l, --level N       compression level 0-9");
     eprintln!(" -p, --parity N      use N (2/4) parity contexts");
+    eprintln!(" -r, --reverse       reverse input & output");
     process::exit(1);
 }