diff --git a/requirements_dev.txt b/requirements_dev.txt
index 8245082..0c6d306 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -5,7 +5,7 @@ watchdog==0.8.3
 flake8==3.0.4
 tox==2.4.1
 coverage==4.2
-Sphinx==2.4.4
+Sphinx==3.5.1
 cryptography==2.0.2
 PyYAML==3.12
 pytest==3.0.3