How to build lxml from source

To build lxml from source, you need libxml2 and libxslt properly installed, including the header files. These are likely shipped in separate -dev or -devel packages like libxml2-dev, which you must install before trying to build lxml.



The lxml.etree and lxml.objectify modules are written in Cython. Since we distribute the Cython-generated .c files with lxml releases, however, you do not need Cython to build lxml from the normal release sources. We even encourage you to not install Cython for a normal release build, as the generated C code can vary quite heavily between Cython versions, which may or may not generate correct code for lxml. The pre-generated release sources were tested and therefore are known to work.

So, if you want a reliable build of lxml, we suggest to a) use a source release of lxml and b) disable or uninstall Cython for the build.

Only if you are interested in building lxml from a checkout of the developer sources (e.g. to test a bug fix that has not been release yet) or if you want to be an lxml developer, then you do need a working Cython installation. You can use pip to install it:

pip install "Cython>=0.17.1"

lxml currently requires Cython 0.17.1, later release versions should work as well.

Github, git and hg

The lxml package is developed in a repository on Github using Mercurial and the hg-git plugin. You can retrieve the current developer version using:

hg clone git:// lxml

This will create a directory lxml and download the source into it, including the complete development history. Don't be afraid, the download is fairly quick. You can also browse the lxml repository through the web.

Building the sources

Clone the source repository as described above (or download the source tar-ball and unpack it) and then type:

python build


python bdist_egg     # requires 'setuptools' or 'distribute'

To (re-)build the C sources with Cython, you must additionally pass the option --with-cython:

python build --with-cython

If you want to test lxml from the source directory, it is better to build it in-place like this:

python build_ext -i --with-cython

or, in Unix-like environments:

make inplace

If you get errors about missing header files (e.g. Python.h or libxml/xmlversion.h) then you need to make sure the development packages of Python, libxml2 and libxslt are properly installed. On Linux distributions, they are usually called something like libxml2-dev or libxslt-devel. If these packages were installed in non-standard places, try passing the following option to to make sure the right config is found:

python build --with-xslt-config=/path/to/xslt-config

If this doesn't help, you may have to add the location of the header files to the include path like:

python build_ext -i  -I /usr/include/libxml2

where the file is in /usr/include/libxml2/libxml/xmlversion.h

To use lxml.etree in-place, you can place lxml's src directory on your Python module search path (PYTHONPATH) and then import lxml.etree to play with it:

# cd lxml
# PYTHONPATH=src python
Python 2.7.2
Type "help", "copyright", "credits" or "license" for more information.
>>> from lxml import etree

To make sure everything gets recompiled cleanly after changes, you can run make clean or delete the file src/lxml/etree.c. Distutils do not automatically pick up changes that affect files other than the main file src/lxml/etree.pyx.

Running the tests and reporting errors

The source distribution (tgz) and the source repository contain a test suite for lxml. You can run it from the top-level directory:


Note that the test script only tests the in-place build (see distutils building above), as it searches the src directory. You can use the following one-step command to trigger an in-place build and test it:

make test

This also runs the ElementTree and cElementTree compatibility tests. To call them separately, make sure you have lxml on your PYTHONPATH first, then run:




If the tests give failures, errors, or worse, segmentation faults, we'd really like to know. Please contact us on the mailing list, and please specify the version of lxml, libxml2, libxslt and Python you were using, as well as your operating system type (Linux, Windows, MacOS-X, ...).

Building an egg

This is the procedure to make an lxml egg for your platform (assuming that you have "setuptools" or "distribute" installed):

This will put the egg into the dist directory.

Building lxml on MacOS-X

Apple regularly ships new system releases with horribly outdated system libraries. This is specifically the case for libxml2 and libxslt, where the system provided versions are too old to build lxml.

While the Unix environment in MacOS-X makes it relatively easy to install Unix/Linux style package management tools and new software, it actually seems to be hard to get libraries set up for exclusive usage that MacOS-X ships in an older version. Alternative distributions (like macports) install their libraries in addition to the system libraries, but the compiler and the runtime loader on MacOS still sees the system libraries before the new libraries. This can lead to undebuggable crashes where the newer library seems to be loaded but the older system library is used.

Apple discourages static building against libraries, which would help working around this problem. Apple does not ship static library binaries with its system and several package management systems follow this decision. Therefore, building static binaries requires building the dependencies first. The script does this automatically when you call it like this:

python build --static-deps

This will download and build the latest versions of libxml2 and libxslt from the official FTP download site. If you want to use specific versions, or want to prevent any online access, you can download both tar.gz release files yourself, place them into a subdirectory libs in the lxml distribution, and call with the desired target versions like this:

python build --static-deps \
       --libxml2-version=2.7.8 \
       --libxslt-version=1.1.27 \

sudo python install

Instead of build, you can use any target, like bdist_egg if you want to use setuptools to build an installable egg.

Note that this also works with pip. Since you can't pass command line options in this case, you have to use an environment variable instead:

STATIC_DEPS=true pip install lxml

To install the package into the system Python package directory, run the installation with "sudo":

STATIC_DEPS=true sudo pip install lxml

The STATICBUILD environment variable is handled equivalently to the STATIC_DEPS variable, but is used by some other extension packages, too.

Static linking on Windows

Most operating systems have proper package management that makes installing current versions of libxml2 and libxslt easy. The most famous exception is Microsoft Windows, which entirely lacks these capabilities. It can therefore be interesting to statically link the external libraries into lxml.etree to avoid having to install them separately.

Download lxml and all required libraries to the same directory. The iconv, libxml2, libxslt, and zlib libraries are all available from the ftp site

Your directory should now have the following files in it (although most likely different versions):

Now extract each of those files in the same directory. This should give you something like this:


Go to the lxml directory and edit the file There should be a section near the top that looks like this:


Change this section to something like this, but take care to use the correct version numbers:




Add any CFLAGS you might consider useful to the third list. Now you should be able to pass the --static option to and everything should work well. Try calling:

python bdist_wininst --static

This will create a windows installer in the pkg directory.

Building Debian packages from SVN sources

Andreas Pakulat proposed the following approach.

In case dpkg-buildpackage tells you that some dependecies are missing, you can either install them manually or run apt-get build-dep lxml.

That will give you .deb packages in the parent directory which can be installed using dpkg -i.