diff --git a/lz16/liblz16.lua b/lz16/liblz16.lua
index a2faaa7..a13ce91 100644
--- a/lz16/liblz16.lua
+++ b/lz16/liblz16.lua
@@ -3,35 +3,17 @@ local buffer = require "buffer"
 
 lz16 = {}
 
-local function cint(n,l)
- local t={}
- for i = 0, 7 do
-  t[i+1] = (n >> (i * 8)) & 0xFF
- end
- return string.reverse(string.char(table.unpack(t)):sub(1,l))
-end
-local function toint(s)
- local n = 0
- local i = 1
- for p in s:gmatch(".") do
-  n = n << 8
-  n = n | string.byte(p)
-  i=i+1
- end
- return n
-end
-
 local function readBuffer(fi)
  local stream = {}
  if fi:read(4) ~= "lz16" then
   return false, "not an lz16 archive"
  end
  function stream.read()
-  local len = toint(fi:read(2) or "\0\0")
+  local len = string.unpack(">I2", fi:read(2) or "\0\0")
   if len < 1 then
    return nil
   end
-  coroutine.yield()
+  if os.sleep then os.sleep(0) else coroutine.yield() end
   return lz.decompress(fi:read(len))
  end
  function stream.close()
@@ -44,7 +26,7 @@ local function writeBuffer(fo)
  local stream = {}
  function stream:write(data)
   local cblock = lz.compress(data)
-  fo:write(cint(cblock:len(),2)..cblock)
+  fo:write(string.pack(">I2", cblock:len()) .. cblock)
   return cblock:len()+2
  end
  function stream.close()
@@ -54,14 +36,14 @@ local function writeBuffer(fo)
  return buffer.new("wb",stream)
 end
 
-function lz16.buffer(stream)
+function lz16.buffer(stream) -- table -- table -- Wrap a stream to read or write LZ16.
  if stream.mode.w then
   return writeBuffer(stream)
  end
  return readBuffer(stream)
 end
 
-function lz16.open(fname, mode)
+function lz16.open(fname, mode) -- string string -- table -- Open file *fname* to read or write LZ16-compressed data depending on *mode*
  local f = io.open(fname, mode)
  if not f then return false end
  f.mode.b = true
diff --git a/mtar/OpenOS/usr/bin/mtar.lua b/mtar/OpenOS/usr/bin/mtar.lua
index 78f29f9..9876ac0 100644
--- a/mtar/OpenOS/usr/bin/mtar.lua
+++ b/mtar/OpenOS/usr/bin/mtar.lua
@@ -7,18 +7,6 @@ local args, opts = shell.parse(...)
 local w, lz16 = pcall(require, "liblz16")
 if not w then lz16 = nil end
 
-local function toint(s)
- s = s or "\0"
- local n = 0
- local i = 1
- for p in s:gmatch(".") do
-  n = n << 8
-  n = n | string.byte(p)
-  i=i+1
- end
- return n
-end
-
 local function vw(s)
  if opts.v and s then
   io.write(tostring(s))
@@ -82,6 +70,9 @@ function open(fn,mode)
  local f
  if opts.z then
   f = lz16.open(fn, mode)
+  if mode == "w" and tonumber(opts.csize) then
+   f.bufferSize = tonumber(opts.csize)
+  end
  else
   f = io.open(fn, mode)
  end
@@ -151,7 +142,7 @@ elseif opts.c then
  f:close()
 else
  print([[Usage:
- mtar -[crtxvz] <archivefile> [otherfile] [otherfile]
+ mtar -[crtxvz] <archivefile> [otherfile] [otherfile] [--csize=blocksize]
 Operations:
  x: extract archive
  c: create archive
@@ -159,5 +150,7 @@ Operations:
 Flags:
  v: be verbose
  z: use LZSS compression (requires liblz16)
- r: append rather than overwrite]])
+ r: append rather than overwrite
+Extended options:
+ csize: compression input block size]])
 end
diff --git a/mtar/OpenOS/usr/man/mtar b/mtar/OpenOS/usr/man/mtar
index 1e9132b..7910963 100644
--- a/mtar/OpenOS/usr/man/mtar
+++ b/mtar/OpenOS/usr/man/mtar
@@ -1,7 +1,7 @@
 # mtar - Minitel Archiver
 ## Usage
 
-    mtar -[crtxvz] <archivefile> [otherfile] [otherfile]
+    mtar -[crtxvz] <archivefile> [otherfile] [otherfile] [--csize=block size]
 
 ## Operations
 
@@ -12,7 +12,10 @@
 ## Flags
 
  v: be verbose  
- z: use LZSS compression (requires liblz16)]])
+ z: use LZSS compression (requires liblz16)
+
+## Extended options:
+ csize: compression input block size
 
 ## Examples
 
diff --git a/mtar/libmtar.lua b/mtar/libmtar.lua
index 9c4adef..4c40335 100644
--- a/mtar/libmtar.lua
+++ b/mtar/libmtar.lua
@@ -1,26 +1,24 @@
 local mtar = {}
+local versions = {}
+versions[0] = {nlf = ">I2", flf = ">I2"} -- original version format
+versions[1] = {nlf = ">I2", flf = ">I8"} -- extended file size format
+mtar.versions = versions
 
-local function toint(s)
- local n = 0
- local i = 1
- for p in s:gmatch(".") do
-  n = n << 8
-  n = n | string.byte(p)
-  i=i+1
+local function cleanPath(path)
+ local pt = {}
+ for segment in path:gmatch("[^/]+") do
+  if segment == ".." then
+   pt[#pt] = nil
+  elseif segment ~= "." then
+   pt[#pt+1] = segment
+  end
  end
- return n
+ return table.concat(pt,"/")
 end
 
-local function cint(n,l)
- local t={}
- for i = 0, 7 do
-  t[i+1] = (n >> (i * 8)) & 0xFF
- end
- return string.reverse(string.char(table.unpack(t)):sub(1,l))
-end
-
-function mtar.genHeader(fname,len) -- string number -- string -- Generates an mtar file header for a file called *name* that is *len* bytes long.
- return string.format("%s%s%s",cint(fname:len(),2),fname,cint(len,2))
+function mtar.genHeader(fname,len,version) -- string number -- string -- generate a header for file *fname* when provided with file length *len*
+ version=version or 1
+ return string.format("\255\255%s%s%s%s", string.char(version), string.pack(versions[version].nlf,fname:len()), fname, string.pack(versions[version].flf,len))
 end
 
 function mtar.iter(stream) -- table -- function -- Given buffer *stream*, returns an iterator suitable for use with *for* that returns, for each iteration, the file name, a function to read from the file, and the length of the file.
@@ -31,15 +29,20 @@ function mtar.iter(stream) -- table -- function -- Given buffer *stream*, return
   return rb
  end
  return function()
-  stream:read(remain)
-  local nlen = toint(stream:read(2) or "\0\0")
+  while remain > 0 do
+   remain=remain-#stream:read(math.min(remain,2048))
+  end
+  local version = 0
+  local nlen = string.unpack(">I2", stream:read(2) or "\0\0")
   if nlen == 0 then
    return
+  elseif nlen == 65535 then -- versioned header
+   version = string.byte(stream:read(1))
+   nlen = string.unpack(versions[version].nlf, stream:read(string.packsize(versions[version].nlf)))
   end
-  local name = stream:read(nlen)
-  local fsize = toint(stream:read(2))
-  remain = fsize
-  return name, read, fsize
+  local name = cleanPath(stream:read(nlen))
+  remain = string.unpack(versions[version].flf, stream:read(string.packsize(versions[version].flf)))
+  return name, read, remain
  end
 end