diff --git a/docs/requirements.txt b/docs/requirements.txt
index ed995c8..2e3aedf 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,5 +1,5 @@
 docutils==0.14
 Pygments==2.2.0
 Sphinx==1.6.3
-sphinxcontrib-spelling==2.3.0
+sphinxcontrib-spelling==4.0.0
 sphinxcontrib-websupport==1.0.1