diff --git a/requirements_dev.txt b/requirements_dev.txt
index eb0e7db..30a69aa 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -17,4 +17,4 @@ PyYAML==3.12
 
 # doc-related
 docutils==0.13.1
-Sphinx==1.6.2
+Sphinx==3.4.2