diff --git a/requirements.txt b/requirements.txt
index 00e2bde..5ff8e8c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ appdirs==1.4.0
 configobj==5.0.6
 google-api-python-client==1.12.8
 httplib2==0.19.0
-nltk==3.4.5
+nltk==3.9
 oauth2client==4.0.0
 packaging==16.8
 pyasn1==0.4.1