diff --git a/extensions/autodoc_placeholder/__init__.py b/extensions/autodoc_placeholder/__init__.py
index 470f53830..1f4e088b2 100644
--- a/extensions/autodoc_placeholder/__init__.py
+++ b/extensions/autodoc_placeholder/__init__.py
@@ -21,6 +21,6 @@ def setup(app):
     directives.register_directive('autoattribute', PlaceHolder)
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
diff --git a/extensions/embedded_video/__init__.py b/extensions/embedded_video/__init__.py
index f200deeed..9119e01c9 100644
--- a/extensions/embedded_video/__init__.py
+++ b/extensions/embedded_video/__init__.py
@@ -66,6 +66,6 @@ def setup(app):
     directives.register_directive('vimeo', Vimeo)
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
diff --git a/extensions/exercise_admonition/__init__.py b/extensions/exercise_admonition/__init__.py
index e16afd94e..fd0b0b6a5 100644
--- a/extensions/exercise_admonition/__init__.py
+++ b/extensions/exercise_admonition/__init__.py
@@ -21,8 +21,9 @@ def setup(app):
     ))
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
 
+
 admonitionlabels['exercise'] = 'Exercise'
diff --git a/extensions/github_link/__init__.py b/extensions/github_link/__init__.py
index 5d1752c5e..6bde1c906 100644
--- a/extensions/github_link/__init__.py
+++ b/extensions/github_link/__init__.py
@@ -75,7 +75,7 @@ def setup(app):
     app.config.linkcode_resolve = linkcode_resolve
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
 
diff --git a/extensions/html_domain/__init__.py b/extensions/html_domain/__init__.py
index 70a38ee79..f3e20b465 100644
--- a/extensions/html_domain/__init__.py
+++ b/extensions/html_domain/__init__.py
@@ -40,7 +40,7 @@ def setup(app):
         addnode(app, node, name)
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
 
diff --git a/extensions/odoo_theme/__init__.py b/extensions/odoo_theme/__init__.py
index 4e61aaefb..041f9a14e 100644
--- a/extensions/odoo_theme/__init__.py
+++ b/extensions/odoo_theme/__init__.py
@@ -16,7 +16,7 @@ def setup(app):
     app.add_js_file('js/page_toc.js')
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
 
diff --git a/extensions/redirects/__init__.py b/extensions/redirects/__init__.py
index 054baf733..f66c6b6fa 100644
--- a/extensions/redirects/__init__.py
+++ b/extensions/redirects/__init__.py
@@ -64,6 +64,6 @@ def setup(app):
     app.connect('builder-inited', generate_redirects)
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
diff --git a/extensions/switcher/__init__.py b/extensions/switcher/__init__.py
index 7ae9b3376..87c36e74b 100644
--- a/extensions/switcher/__init__.py
+++ b/extensions/switcher/__init__.py
@@ -13,7 +13,7 @@ def setup(app):
     app.connect('env-updated', add_statics)
 
     return {
-        'parallel_read_safe': True,
+        'parallel_read_safe': False,
         'parallel_write_safe': True
     }
 
@@ -21,10 +21,12 @@ def add_statics(app, env):
     app.add_js_file('js/switcher.js')
     env.config.html_static_path.append(statics())
 
+
 statics = lambda *p: os.path.join(
     os.path.abspath(os.path.dirname(__file__)),
     'static', *p)
 
+
 class SwitcherDirective(Directive):
     has_content = True