diff --git a/requirements.txt b/requirements.txt
index 55df609..e8e74c7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 h5py==2.7.1
-nltk==3.4.5
+nltk==3.6.6
 pandas==0.19.1
 scipy==1.0.0
 Keras==2.1.4