diff --git a/docs/requirements.txt b/docs/requirements.txt
index 39fb15a..a133a73 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -27,7 +27,7 @@ mock==4.0.1
 more-itertools==8.2.0
 mypy==0.761
 mypy-extensions==0.4.3
-nltk==3.6.6; python_version > "2.7"
+nltk==3.9.4; python_version > "2.7"
 packaging==20.3
 pathspec==0.7.0
 pluggy==0.13.1