diff --git a/doc-requirements.txt b/doc-requirements.txt
index c0ee2014cf64..58a5c698043b 100644
--- a/doc-requirements.txt
+++ b/doc-requirements.txt
@@ -6,7 +6,7 @@
 # Install the documentation requirements with:
 #     pip install -r doc-requirements.txt
 #
-sphinx>=1.3,!=1.5.0,!=1.6.4,!=1.7.3
+sphinx>=1.3,!=1.5.0,!=1.6.4,!=1.7.3,<1.8
 colorspacious
 ipython
 ipywidgets
diff --git a/doc/conf.py b/doc/conf.py
index 111a61aae7e7..3e6dc476b09f 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -37,6 +37,7 @@
     'IPython.sphinxext.ipython_directive',
     'numpydoc',  # Needs to be loaded *after* autodoc.
     'sphinx_gallery.gen_gallery',
+    'matplotlib.sphinxext.mathmpl',
     'matplotlib.sphinxext.plot_directive',
     'sphinxext.custom_roles',
     'sphinxext.github',
@@ -44,8 +45,6 @@
     'sphinxext.mock_gui_toolkits',
     'sphinxext.skip_deprecated',
 ]
-if sphinx.version_info < (1, 8):
-    extensions.append('matplotlib.sphinxext.mathmpl')
 
 exclude_patterns = ['api/api_changes/*', 'users/whats_new/*']