diff --git a/doc/source/conf.py b/doc/source/conf.py
index 7dd61d33b8..04fd5f5029 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -29,7 +29,7 @@ sys.path.extend([os.path.abspath('../swift'), os.path.abspath('..'),
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['sphinx.ext.autodoc',
-              'sphinx.ext.todo', 'sphinx.ext.coverage', 'sphinx.ext.pngmath',
+              'sphinx.ext.todo', 'sphinx.ext.coverage',
               'sphinx.ext.ifconfig', 'oslosphinx']
 todo_include_todos = True