diff --git a/requirements.txt b/requirements.txt
index 4531a0c..531d87e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 Keras==2.1.2
 tensorflow==1.4.0
-nltk==3.2.5
+nltk==3.6.3
 opencv-python==3.3.0.10
 numpy==1.13.1
 h5py==2.7.1