diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index 58221c28f2..625dbaf9af 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -76,8 +76,8 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
       # Use more than 4 characters to not clash with magicbytes
       magic_bytes = "____pkg"
     else
-      # get the first four bytes
-      File.open(@tarball_path) { |f| magic_bytes = f.read(4) }
+      # get the first six bytes
+      File.open(@tarball_path) { |f| magic_bytes = f.read(6) }
     end
 
     # magic numbers stolen from /usr/share/file/magic/
@@ -89,6 +89,10 @@ class CurlDownloadStrategy < AbstractDownloadStrategy
       # TODO check if it's really a tar archive
       safe_system '/usr/bin/tar', 'xf', @tarball_path
       chdir
+    when /^\xFD7zXZ\x00/ # xz compressed
+      raise "You must install XZutils: brew install xz" unless system "/usr/bin/which -s xz"
+      safe_system "xz -dc #{@tarball_path} | /usr/bin/tar xf -"
+      chdir
     when '____pkg'
       safe_system '/usr/sbin/pkgutil', '--expand', @tarball_path, File.basename(@url)
       chdir
diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 65d34d4500..018547ff80 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -62,9 +62,9 @@ class Pathname
     return dst
   end
 
-  # extended to support the double extensions .tar.gz and .tar.bz2
+  # extended to support the double extensions .tar.gz, .tar.bz2, and .tar.xz
   def extname
-    /(\.tar\.(gz|bz2))$/.match to_s
+    /(\.tar\.(gz|bz2|xz))$/.match to_s
     return $1 if $1
     return File.extname(to_s)
   end
diff --git a/Library/Homebrew/test/test_bucket.rb b/Library/Homebrew/test/test_bucket.rb
index 010c06761d..f328dacca1 100644
--- a/Library/Homebrew/test/test_bucket.rb
+++ b/Library/Homebrew/test/test_bucket.rb
@@ -32,8 +32,10 @@ class BeerTasting < Test::Unit::TestCase
     assert_nothing_raised do
       MockFormula.new 'test-0.1.tar.gz'
       MockFormula.new 'test-0.1.tar.bz2'
+      MockFormula.new 'test-0.1.tar.xz'
       MockFormula.new 'test-0.1.tgz'
       MockFormula.new 'test-0.1.bgz'
+      MockFormula.new 'test-0.1.txz'
       MockFormula.new 'test-0.1.zip'
     end
   end