diff --git a/requirements.txt b/requirements.txt
index 2412d12..b51f6f0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -53,7 +53,7 @@ MarkupSafe==1.0
 mccabe==0.6.1
 natsort==5.1.0
 nbformat==4.4.0
-nltk==3.2.5
+nltk==3.4.5
 numpy==1.13.3
 oauth2client==4.1.2
 oauthlib==2.0.2