diff --git a/requirements.txt b/requirements.txt
index 3f1267b..78d4377 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -25,7 +25,7 @@ Jinja2>=2.10.1
 Markdown==2.6.11
 MarkupSafe==1.0
 matplotlib==2.1.2
-nltk==3.2.5
+nltk==3.6.5
 numpy==1.14.0
 oauth2client==4.1.2
 pandas==0.22.0