diff --git a/hyperbox/networks/nasbench301/install/requirements_cu111.txt b/hyperbox/networks/nasbench301/install/requirements_cu111.txt
index f0106b1..ac11aee 100644
--- a/hyperbox/networks/nasbench301/install/requirements_cu111.txt
+++ b/hyperbox/networks/nasbench301/install/requirements_cu111.txt
@@ -122,7 +122,7 @@ nbconvert==5.4.0
 nbformat==4.4.0
 netifaces==0.10.9
 networkx==2.1
-nltk==3.3
+nltk==3.6.6
 nni==1.9
 nodeenv==1.6.0
 nose==1.3.7