diff --git a/headers.js b/headers.js
index d786148..8aab8b5 100644
--- a/headers.js
+++ b/headers.js
@@ -132,10 +132,13 @@ function parse256 (buf) {
   return positive ? sum : -1 * sum
 }
 
-var decodeOct = function (val, offset) {
+var decodeOct = function (val, offset, length) {
+  val = val.slice(offset, offset + length)
+  offset = 0
+
   // If prefixed with 0x80 then parse as a base-256 integer
   if (val[offset] & 0x80) {
-    return parse256(val.slice(offset, offset + 8))
+    return parse256(val)
   } else {
     // Older versions of tar can prefix with spaces
     while (offset < val.length && val[offset] === 32) offset++
@@ -241,17 +244,17 @@ exports.decode = function (buf) {
   var typeflag = buf[156] === 0 ? 0 : buf[156] - ZERO_OFFSET
 
   var name = decodeStr(buf, 0, 100)
-  var mode = decodeOct(buf, 100)
-  var uid = decodeOct(buf, 108)
-  var gid = decodeOct(buf, 116)
-  var size = decodeOct(buf, 124)
-  var mtime = decodeOct(buf, 136)
+  var mode = decodeOct(buf, 100, 8)
+  var uid = decodeOct(buf, 108, 8)
+  var gid = decodeOct(buf, 116, 8)
+  var size = decodeOct(buf, 124, 12)
+  var mtime = decodeOct(buf, 136, 12)
   var type = toType(typeflag)
   var linkname = buf[157] === 0 ? null : decodeStr(buf, 157, 100)
   var uname = decodeStr(buf, 265, 32)
   var gname = decodeStr(buf, 297, 32)
-  var devmajor = decodeOct(buf, 329)
-  var devminor = decodeOct(buf, 337)
+  var devmajor = decodeOct(buf, 329, 8)
+  var devminor = decodeOct(buf, 337, 8)
 
   if (buf[345]) name = decodeStr(buf, 345, 155) + '/' + name
 
@@ -264,7 +267,7 @@ exports.decode = function (buf) {
   if (c === 8 * 32) return null
 
   // valid checksum
-  if (c !== decodeOct(buf, 148)) throw new Error('Invalid tar header. Maybe the tar is corrupted or it needs to be gunzipped?')
+  if (c !== decodeOct(buf, 148, 8)) throw new Error('Invalid tar header. Maybe the tar is corrupted or it needs to be gunzipped?')
 
   return {
     name: name,