diff --git a/requirements-mkdocs.txt b/requirements-mkdocs.txt
index 2d37ea3523681..775ad612b75dd 100644
--- a/requirements-mkdocs.txt
+++ b/requirements-mkdocs.txt
@@ -17,7 +17,7 @@ mkdocs-macros-test==0.1.0
 mkdocs-material==7.0.6
 mkdocs-material-extensions==1.0.1
 mkdocs-minify-plugin==0.3.0
-nltk==3.5
+nltk==3.6.5
 Pygments==2.7.4
 pymdown-extensions==8.1
 python-dateutil==2.8.1