diff --git a/requirements.txt b/requirements.txt
index 77df8f9..00a4934 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -34,7 +34,7 @@ mistune==0.8.1
 mock==2.0.0
 nbconvert==5.3.1
 nbformat==4.4.0
-nltk==3.2.5
+nltk==3.4.5
 notebook==5.2.1
 numpy==1.13.3
 pandas==0.21.0