diff --git a/requirements.txt b/requirements.txt
index 361f4fe..bcad211 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -44,7 +44,7 @@ msgpack-numpy==0.4.3.1
 murmurhash==0.28.0
 nbconvert==5.3.1
 nbformat==4.4.0
-nltk==3.3
+nltk==3.4.5
 notebook==5.6.0
 numpy==1.14.5
 pandas==0.23.3