diff --git a/NLP/ACL2020-GraphSum/requirements.txt b/NLP/ACL2020-GraphSum/requirements.txt
index 3f1fd3cfe..311930942 100644
--- a/NLP/ACL2020-GraphSum/requirements.txt
+++ b/NLP/ACL2020-GraphSum/requirements.txt
@@ -1,4 +1,4 @@
-nltk==3.4.5
+nltk==3.6.6
 numpy==1.18.1
 paddlepaddle-gpu==1.6.3.post107
 pyrouge==0.1.3