diff --git a/.circleci/config.yml b/.circleci/config.yml
index 21e40b1..6891d0b 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -11,7 +11,9 @@ commands:
         default: "21,22,23,24,30,31,32,33,34,35,40,41,42,43,44,latest"
     steps:
       - checkout
-      - run: pip install --user tox
+      # NOTE: update tox to tox<5 when https://github.com/tox-dev/tox/issues/2850
+      # is fixed.
+      - run: pip install --user 'tox<4'
       - run: tox -e "<<parameters.version>>-sphinx{<<parameters.sphinx-version>>}"
 
 jobs:
diff --git a/readthedocs_ext/readthedocs.py b/readthedocs_ext/readthedocs.py
index dfaf4c0..6243893 100644
--- a/readthedocs_ext/readthedocs.py
+++ b/readthedocs_ext/readthedocs.py
@@ -7,11 +7,9 @@
 import os
 import re
 import types
-from datetime import datetime
 from packaging.version import Version
 
 import sphinx
-from sphinx import package_dir
 from sphinx.util.console import bold
 
 
@@ -157,9 +155,7 @@ def rtd_render(self, template, render_context):
                 'source_suffix': ctx.get('source_suffix', ''),
                 'page': ctx.get('pagename', ''),
                 'api_host': ctx.get('api_host', ''),
-                'commit': ctx.get('commit', ''),
                 'ad_free': ctx.get('ad_free', ''),
-                'build_date': datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%SZ'),
                 'global_analytics_code': ctx.get('global_analytics_code'),
                 'user_analytics_code': ctx.get('user_analytics_code'),
                 'subprojects': dict(ctx.get('subprojects', [])),