diff --git a/requirements.txt b/requirements.txt
index f9e86e0..18dbf8d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -54,7 +54,7 @@ mock==2.0.0
 nbconvert==5.3.1
 nbformat==4.4.0
 networkx==2.1
-nltk==3.3
+nltk==3.4.5
 notebook==5.4.1
 numexpr==2.6.7
 numpy==1.14.2