diff --git a/requirements.txt b/requirements.txt
index 46591a3..01982b4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -20,7 +20,7 @@ MarkupSafe==0.23
 matplotlib==1.4.3
 mock==1.3.0
 ndg-httpsclient==0.4.0
-nltk==3.0.4
+nltk==3.6.3
 nose==1.3.7
 numpy==1.9.2
 oauth==1.0.1