diff --git a/APIs-Backend/requirements.txt b/APIs-Backend/requirements.txt
index f5d5bfb..df51e03 100644
--- a/APIs-Backend/requirements.txt
+++ b/APIs-Backend/requirements.txt
@@ -5,7 +5,7 @@ elasticsearch==5.4.0
 funcsigs==1.0.2
 gunicorn==19.7.1
 mock==2.0.0
-nltk==3.2.4
+nltk==3.4.5
 numpy==1.13.1
 packaging==16.8
 pbr==3.1.1