diff --git a/headers.js b/headers.js
index e688f93..e6164c6 100644
--- a/headers.js
+++ b/headers.js
@@ -1,6 +1,7 @@
 var ZEROS = '0000000000000000000'
 var ZERO_OFFSET = '0'.charCodeAt(0)
 var USTAR = 'ustar\x0000'
+var MASK = parseInt('7777', 8)
 
 var clamp = function(index, len, defaultValue) {
   if (typeof index !== 'number') return defaultValue
@@ -166,7 +167,7 @@ exports.encode = function(opts) {
   if (opts.linkname && Buffer.byteLength(opts.linkname) > 100) return null
 
   buf.write(name)
-  buf.write(encodeOct(opts.mode & parseInt('07777', 8), 6), 100)
+  buf.write(encodeOct(opts.mode & MASK, 6), 100)
   buf.write(encodeOct(opts.uid, 6), 108)
   buf.write(encodeOct(opts.gid, 6), 116)
   buf.write(encodeOct(opts.size, 11), 124)
diff --git a/pack.js b/pack.js
index 043f28d..0dd84cf 100644
--- a/pack.js
+++ b/pack.js
@@ -9,6 +9,8 @@ var StringDecoder = require('string_decoder').StringDecoder
 
 var headers = require('./headers')
 
+var DMODE = parseInt('755', 8)
+var FMODE = parseInt('644', 8)
 
 var END_OF_TAR = new Buffer(1024)
 END_OF_TAR.fill(0)
@@ -118,7 +120,7 @@ Pack.prototype.entry = function(header, buffer, callback) {
 
   if (!header.size)  header.size = 0
   if (!header.type)  header.type = modeToType(header.mode)
-  if (!header.mode)  header.mode = parseInt(header.type === 'directory' ? '0755' : '0644')
+  if (!header.mode)  header.mode = header.type === 'directory' ? DMODE : FMODE
   if (!header.uid)   header.uid = 0
   if (!header.gid)   header.gid = 0
   if (!header.mtime) header.mtime = new Date()