diff --git a/requirements.txt b/requirements.txt
index 2dc33f5..e2a56d5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,7 +9,7 @@ ipython-genutils==0.2.0
 jsonschema==2.6.0
 jupyter-core==4.3.0
 nbformat==4.4.0
-nltk==3.2.5
+nltk==3.4.5
 numpy==1.13.1
 oauth2client==4.1.2
 pandas==0.20.3