diff --git a/docs/requirements.txt b/docs/requirements.txt
index 58a6570..a636b41 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
-Sphinx==3.0.4
+Sphinx==3.3.0
 sphinx-rtd-theme==0.3.0
 sphinxcontrib-phpdomain==0.4.1
 doxyphp2sphinx>=1.0.1