diff --git a/docs/conf.py b/docs/conf.py
index cbbf800..41c0f83 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -297,4 +297,5 @@ locale_dirs = ['locale/']
 gettext_compact = False
 
 def setup(app):
-    app.add_stylesheet('css/custom.css')
\ No newline at end of file
+    app.add_css_file('css/custom.css')
+
diff --git a/requirements.txt b/requirements.txt
index 5a548c1..47ea247 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-Sphinx>=1.3.6
+Sphinx>=4.1.1
 sphinx_rtd_theme
 sphinx-intl