diff --git a/notebooks/requirements.txt b/notebooks/requirements.txt
index b82a389..331757a 100644
--- a/notebooks/requirements.txt
+++ b/notebooks/requirements.txt
@@ -175,7 +175,7 @@ navigator-updater==0.2.1
 nbconvert==5.5.0
 nbformat==4.4.0
 networkx==2.3
-nltk==3.2.4
+nltk==3.4.5
 nose==1.3.7
 notebook==6.0.0
 num2words==0.5.5