diff --git a/requirements.txt b/requirements.txt
index b2641c71..52977f34 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -135,7 +135,7 @@ nbconvert==6.5.1
 nbformat==5.0.7
 nereval==0.2.5
 networkx==2.6.3
-nltk==3.4.4
+nltk==3.9.4
 node2vec==0.4.3
 nose==1.3.7
 notebook==6.4.12