diff --git a/requirements.txt b/requirements.txt
index 59a4ab1..ed9fe3b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -24,7 +24,7 @@ MarkupSafe==1.0
 mercurial==4.5.3
 mock==2.0.0
 mongoengine==0.15.0
-nltk==3.2.5
+nltk==3.4.5
 nose==1.3.7
 oauth2client==4.1.2
 packaging==17.1