switch to env variable based static/dynamic switch for windows
diff --git a/docs/installation.rst b/docs/installation.rst
index 56d21e7..81e150d 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -45,13 +45,25 @@
If you prefer to compile it yourself you'll need to have OpenSSL installed.
There are `pre-compiled binaries`_ available. If your installation is in an
unusual location set the ``LIB`` and ``INCLUDE`` environment variables to
-include the corresponding locations. For example:
+include the corresponding locations.For example:
.. code-block:: console
C:\> \path\to\vcvarsall.bat x86_amd64
- C:\> set LIB=C:\OpenSSL-1.0.1h-64bit\lib\VC\static;%LIB%
- C:\> set INCLUDE=C:\OpenSSL-1.0.1h-64bit\include;%INCLUDE%
+ C:\> set LIB=C:\OpenSSL\lib\VC\static;C:\OpenSSL\lib;%LIB%
+ C:\> set INCLUDE=C:\OpenSSL\include;%INCLUDE%
+ C:\> pip install cryptography
+
+You can also choose to build statically or dynamically using the
+``PYCA_OPENSSL_INSTALL`` variable. Allowed values are ``static`` (default) and
+``dynamic``.
+
+.. code-block:: console
+
+ C:\> \path\to\vcvarsall.bat x86_amd64
+ C:\> set LIB=C:\OpenSSL\lib\VC\static;C:\OpenSSL\lib;%LIB%
+ C:\> set INCLUDE=C:\OpenSSL\include;%INCLUDE%
+ C:\> set PYCA_OPENSSL_INSTALL=dynamic
C:\> pip install cryptography
Building cryptography on Linux