diff --git a/harvester/requirements.txt b/harvester/requirements.txt
index 5389caa..01e07f2 100644
--- a/harvester/requirements.txt
+++ b/harvester/requirements.txt
@@ -2,7 +2,7 @@ certifi==2018.4.16
 chardet==3.0.4
 CouchDB==1.2
 idna==2.6
-nltk==3.2.5
+nltk==3.4.5
 oauthlib==2.0.7
 PySocks==1.6.8
 requests==2.18.4