diff --git a/setup/install.py b/setup/install.py
index cceab05ab7..9bf8fa9505 100644
--- a/setup/install.py
+++ b/setup/install.py
@@ -283,8 +283,7 @@ class Install(Develop):
 class Sdist(Command):
 
     description = 'Create a source distribution'
-    DEST = os.path.join('dist', '%s-%s.tar.gz'%(__appname__, __version__))
-
+    DEST = os.path.join('dist', '%s-%s.tar.xz'%(__appname__, __version__))
 
     def run(self, opts):
         if not self.e(self.d(self.DEST)):
@@ -313,7 +312,7 @@ class Sdist(Command):
                 shutil.copy2(f, dest)
 
         self.info('\tCreating tarfile...')
-        subprocess.check_call(['tar', '-czf', self.a(self.DEST),
+        subprocess.check_call(['tar', '-cJf', self.a(self.DEST),
             'calibre'], cwd=self.d(tdir))
 
     def clean(self):
diff --git a/setup/upload.py b/setup/upload.py
index ade71ef753..a79b080637 100644
--- a/setup/upload.py
+++ b/setup/upload.py
@@ -25,12 +25,12 @@ MOBILEREAD = 'ftp://dev.mobileread.com/calibre/'
 def installers():
     installers = list(map(installer_name, ('dmg', 'msi', 'tar.bz2')))
     installers.append(installer_name('tar.bz2', is64bit=True))
-    installers.insert(0, 'dist/%s-%s.tar.gz'%(__appname__, __version__))
+    installers.insert(0, 'dist/%s-%s.tar.xz'%(__appname__, __version__))
     installers.append('dist/%s-portable-%s.zip'%(__appname__, __version__))
     return installers
 
 def installer_description(fname):
-    if fname.endswith('.tar.gz'):
+    if fname.endswith('.tar.xz'):
         return 'Source code'
     if fname.endswith('.tar.bz2'):
         bits = '32' if 'i686' in fname else '64'
@@ -117,7 +117,7 @@ class UploadToGoogleCode(Command): # {{{
 
     def re_upload(self):
         fnames = set([os.path.basename(x) for x in installers() if not
-                x.endswith('.tar.gz') and os.path.exists(x)])
+                x.endswith('.tar.xz') and os.path.exists(x)])
         existing = set(self.old_files.keys()).intersection(fnames)
         br = self.login_to_gmail()
         for x in fnames:
@@ -134,11 +134,11 @@ class UploadToGoogleCode(Command): # {{{
 
     def upload_one(self, fname):
         self.info('\nUploading', fname)
-        typ = 'Type-' + ('Source' if fname.endswith('.gz') else 'Archive' if
+        typ = 'Type-' + ('Source' if fname.endswith('.xz') else 'Archive' if
                 fname.endswith('.zip') else 'Installer')
         ext = os.path.splitext(fname)[1][1:]
         op  = 'OpSys-'+{'msi':'Windows','zip':'Windows',
-                'dmg':'OSX','bz2':'Linux','gz':'All'}[ext]
+                'dmg':'OSX','bz2':'Linux','xz':'All'}[ext]
         desc = installer_description(fname)
         start = time.time()
         for i in range(5):
@@ -475,11 +475,11 @@ class UploadToServer(Command): # {{{
     description = 'Upload miscellaneous data to calibre server'
 
     def run(self, opts):
-        check_call('ssh divok rm -f %s/calibre-\*.tar.gz'%DOWNLOADS, shell=True)
-        #check_call('scp dist/calibre-*.tar.gz divok:%s/'%DOWNLOADS, shell=True)
-        check_call('gpg --armor --detach-sign dist/calibre-*.tar.gz',
+        check_call('ssh divok rm -f %s/calibre-\*.tar.xz'%DOWNLOADS, shell=True)
+        #check_call('scp dist/calibre-*.tar.xz divok:%s/'%DOWNLOADS, shell=True)
+        check_call('gpg --armor --detach-sign dist/calibre-*.tar.xz',
                 shell=True)
-        check_call('scp dist/calibre-*.tar.gz.asc divok:%s/signatures/'%DOWNLOADS,
+        check_call('scp dist/calibre-*.tar.xz.asc divok:%s/signatures/'%DOWNLOADS,
                 shell=True)
         check_call('ssh divok bzr update /usr/local/calibre',
                    shell=True)
diff --git a/src/calibre/manual/faq.rst b/src/calibre/manual/faq.rst
index 4fc13ef80d..9516be8931 100644
--- a/src/calibre/manual/faq.rst
+++ b/src/calibre/manual/faq.rst
@@ -89,6 +89,10 @@ Then just add this HTML file to the GUI and use the convert button to create you
 
 .. note:: By default, when adding HTML files, |app| follows links in the files in *depth first* order. This means that if file A.html links to B.html and C.html and D.html, but B.html also links to D.html, then the files will be in the order A.html, B.html, D.html, C.html. If instead you want the order to be A.html, B.html, C.html, D.html then you must tell |app| to add your files in *breadth first* order. Do this by going to Preferences->Plugins and customizing the HTML to ZIP plugin.
 
+The EPUB I produced with |app| is not valid?
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+|app| does not guarantee that an EPUB produced by it is valid. The only guarantee it makes is that if you feed it valid XHTML 1.1 + CSS 2.1 it will output a valid EPUB. |app| is designed for ebook consumers, not producers. It tries hard to ensure that EPUBs it produces actually work as intended on a wide variety of devices, a goal that is incompatible with producing valid EPUBs, and one that is far more important to the vast majority of its users. If you need a tool that always produces valid EPUBs, |app| is not for you.
 
 How do I use some of the advanced features of the conversion tools?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~