diff --git a/compare-variants b/compare-variants
index 87cee5e..f31260c 100755
--- a/compare-variants
+++ b/compare-variants
@@ -2,7 +2,9 @@
 
 configs = [
     [:master, '-b'],
-    [:z80, '-b']
+    [:z80, '-b'],
+    [:z80, ['-b', '-r']],
+    ['old-prob-update', '-b']
 ]
 
 files = Dir[ARGV[0] + '/*'].select {|f| !(f =~ /\.txt$/) }
@@ -34,8 +36,8 @@ for config in configs
     config_results = []
     results << config_results
     for file in files
-        if system('cargo', 'run', '--release', 'pack', '-l', '9', config[1], file, '/tmp/out.upk') &&
-            system('cargo', 'run', '--release', 'unpack', config[1], '/tmp/out.upk', '/tmp/out.bin') &&
+        if system(*['cargo', 'run', '--release', 'pack', config[1], file, '/tmp/out.upk'].flatten) &&
+            system(*['cargo', 'run', '--release', 'unpack', config[1], '/tmp/out.upk', '/tmp/out.bin'].flatten) &&
             File.read(file) == File.read('/tmp/out.bin')
             size = File.size('/tmp/out.upk')
             config_results << size
diff --git a/src/main.rs b/src/main.rs
index 711cb32..b809969 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,12 +10,16 @@ fn main() -> Result<()> {
         Some("pack") => {
             let level = args.opt_value_from_str(["-l", "--level"])?.unwrap_or(2u8);
             let use_bitstream = args.contains(["-b", "--bitstream"]);
+            let reverse = args.contains(["-r", "--reverse"]);
 
             let infile = args.free_from_os_str::<PathBuf, bool>(|s| Ok(s.into()))?;
             let outfile = args.free_from_os_str::<PathBuf, bool>(|s| Ok(s.into()))?;
 
             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);
@@ -39,14 +43,18 @@ fn main() -> Result<()> {
         }
         Some("unpack") => {
             let use_bitstream = args.contains(["-b", "--bitstream"]);
+            let reverse = args.contains(["-r", "--reverse"]);
 
             let infile = args.free_from_os_str::<PathBuf, bool>(|s| Ok(s.into()))?;
             let outfile = args.free_from_os_str::<PathBuf, bool>(|s| Ok(s.into()))?;
 
             let mut data = vec![];
             File::open(infile)?.read_to_end(&mut data)?;
-            let packed_data = upkr::unpack(&data, use_bitstream);
-            File::create(outfile)?.write_all(&packed_data)?;
+            let mut unpacked_data = upkr::unpack(&data, use_bitstream);
+            if reverse {
+                unpacked_data.reverse();
+            }
+            File::create(outfile)?.write_all(&unpacked_data)?;
         }
         Some(other) => {
             bail!("Unknown subcommand '{}'", other);