diff --git a/sub2/backend/requirements.txt b/sub2/backend/requirements.txt
index 0a4688b..14e269b 100644
--- a/sub2/backend/requirements.txt
+++ b/sub2/backend/requirements.txt
@@ -41,7 +41,7 @@ kiwisolver==1.0.1
 konlpy==0.5.2
 nbformat==4.4.0
 networkx==2.2
-nltk==3.4
+nltk==3.4.5
 nose==1.3.7
 notebook==5.7.8
 numba==0.42.0