diff -up libmypaint-1.3.0/doc/source/conf.py.sphinx18 libmypaint-1.3.0/doc/source/conf.py
--- libmypaint-1.3.0/doc/source/conf.py.sphinx18	2016-11-09 19:03:36.000000000 +0100
+++ libmypaint-1.3.0/doc/source/conf.py	2019-03-09 01:07:52.632220351 +0100
@@ -27,7 +27,7 @@ import os
 
 # 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.doctest', 'sphinx.ext.intersphinx', 'sphinx.ext.todo', 'sphinx.ext.coverage', 'sphinx.ext.pngmath', 'sphinx.ext.ifconfig', 'sphinx.ext.viewcode']
+extensions = ['sphinx.ext.autodoc', 'sphinx.ext.doctest', 'sphinx.ext.intersphinx', 'sphinx.ext.todo', 'sphinx.ext.coverage', 'sphinx.ext.imgmath', 'sphinx.ext.ifconfig', 'sphinx.ext.viewcode']
 
 # Breathe setup, for integrating doxygen content
 extensions.append('breathe')