diff --git a/code/requirements.txt b/code/requirements.txt
index b3bb47a..d357428 100644
--- a/code/requirements.txt
+++ b/code/requirements.txt
@@ -1,6 +1,6 @@
 numpy==1.16.2
 torch==1.2.0
-nltk==3.4
+nltk==3.9
 pycocoevalcap==1.0
 h5py==2.9.0
 matplotlib==3.0.3