diff --git a/requirements.txt b/requirements.txt
index 8dbbeb4..d2d51f6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -57,7 +57,7 @@ mistune==0.8.4
 more-itertools==7.2.0
 nbconvert==5.6.0
 nbformat==4.4.0
-nltk==3.4
+nltk==3.6.3
 notebook==6.0.1
 numpy==1.16.1
 pandas==0.25.1