diff --git a/requirements.txt b/requirements.txt
index 5c58c5a4..65b8a46f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -82,7 +82,7 @@ mysqlclient==1.3.10
 nbconvert==5.3.1
 nbformat==4.4.0
 networkx==2.0
-nltk==3.2.5
+nltk==3.6.3
 nose==1.3.7
 notebook==5.1.0
 numpy==1.13.3