diff --git a/doc/sphinxext/gen_gallery.py b/doc/sphinxext/gen_gallery.py
index 54cf342d1f71..9992e788f2f3 100644
--- a/doc/sphinxext/gen_gallery.py
+++ b/doc/sphinxext/gen_gallery.py
@@ -168,3 +168,6 @@ def setup(app):
         app.add_config_value('mpl_example_sections', [], True)
     except sphinx.errors.ExtensionError:
         pass # mpl_example_sections already defined
+
+    metadata = {'parallel_read_safe': True, 'parallel_write_safe': True}
+    return metadata
diff --git a/doc/sphinxext/gen_rst.py b/doc/sphinxext/gen_rst.py
index 42598d2149f7..eff0709f1b6f 100644
--- a/doc/sphinxext/gen_rst.py
+++ b/doc/sphinxext/gen_rst.py
@@ -169,3 +169,6 @@ def setup(app):
         app.add_config_value('mpl_example_sections', [], True)
     except sphinx.errors.ExtensionError:
         pass # mpl_example_sections already defined
+
+    metadata = {'parallel_read_safe': True, 'parallel_write_safe': True}
+    return metadata
diff --git a/doc/sphinxext/github.py b/doc/sphinxext/github.py
index 519e146d198f..8f0ffc0d9782 100644
--- a/doc/sphinxext/github.py
+++ b/doc/sphinxext/github.py
@@ -143,7 +143,7 @@ def ghcommit_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
 
 def setup(app):
     """Install the plugin.
-    
+
     :param app: Sphinx application context.
     """
     app.info('Initializing GitHub plugin')
@@ -152,4 +152,6 @@ def setup(app):
     app.add_role('ghuser', ghuser_role)
     app.add_role('ghcommit', ghcommit_role)
     app.add_config_value('github_project_url', None, 'env')
-    return
+
+    metadata = {'parallel_read_safe': True, 'parallel_write_safe': True}
+    return metadata