diff --git a/requirements.txt b/requirements.txt
index 7e597fc..52b2932 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 torch==0.4.0
-nltk==3.4.5
+nltk==3.9
 tensorboardX==0.8
 torchtext==0.2.3