diff --git a/requirements_py2.7.txt b/requirements_py2.7.txt
index b547b4b..55cf5dd 100644
--- a/requirements_py2.7.txt
+++ b/requirements_py2.7.txt
@@ -121,7 +121,7 @@ navigator-updater==0.2.1
 nbconvert==5.4.1
 nbformat==4.4.0
 networkx==2.2
-nltk==3.4
+nltk==3.4.5
 nose==1.3.7
 notebook==5.7.8
 np-utils==0.5.11.1