diff --git a/doc/source/conf.py b/doc/source/conf.py
index 422f03c..9e0d2c7 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -25,7 +25,7 @@
 
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
-extensions = [ 'sphinxcontrib.blockdiag' ]
+extensions = [ 'sphinxcontrib.blockdiag', 'sphinxcontrib.programoutput' ]
 #extensions = ['sphinx.ext.intersphinx']
 #intersphinx_mapping = {'python': ('http://docs.python.org/2.7', None)}