diff --git a/backend/requirements.txt b/backend/requirements.txt
index 9824023..f638206 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -128,7 +128,7 @@ navigator-updater==0.1.0
 nbconvert==5.1.1
 nbformat==4.3.0
 networkx==1.11
-nltk==3.2.3
+nltk==3.4.5
 nose==1.3.7
 notebook==5.0.0
 numba==0.33.0