diff --git a/python/requirements.txt b/python/requirements.txt
index 7c3791783..035330cda 100644
--- a/python/requirements.txt
+++ b/python/requirements.txt
@@ -22,7 +22,7 @@ MarkupSafe==1.1.1
 mccabe==0.6.1
 mkdocs==1.1
 more-itertools==8.2.0
-nltk==3.4.5
+nltk==3.6.6
 packaging==20.3
 pkginfo==1.5.0.1
 pluggy==0.13.1