diff --git a/requirements.txt b/requirements.txt
index 96d62e7a..1507164a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -60,7 +60,7 @@ marshmallow==2.16.3
 marshmallow-polyfield==3.1
 marshmallow-sqlalchemy==0.10.0
 mock==1.3.0
-nltk==3.8.1
+nltk==3.9
 nose==1.3.7
 odfpy==1.4.1
 openpyxl==3.0.3