diff --git a/requirements-worker.txt b/requirements-worker.txt
index 5cf8e46..4e3123f 100644
--- a/requirements-worker.txt
+++ b/requirements-worker.txt
@@ -56,7 +56,7 @@ Mako==1.1.3
 Markdown==3.3.3
 MarkupSafe==1.1.1
 mock==4.0.3
-nltk==3.5
+nltk==3.6.6
 numpy==1.19.4
 oauthlib==3.1.0
 omp-wrapper==0.7