diff --git a/docs/requirements.in b/docs/requirements.in
index 0d74803..192310d 100644
--- a/docs/requirements.in
+++ b/docs/requirements.in
@@ -1,4 +1,4 @@
 pip-tools==6.4.0
-sphinx==2.0.0
-sphinx-rtd-theme==0.4.3
-sphinxcontrib-plantuml==0.15
+sphinx==4.2.0
+sphinx-rtd-theme==1.0.0
+sphinxcontrib-plantuml==0.22