diff --git a/requirements.txt b/requirements.txt
index 3c06c8b..591c4cf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 h5py==2.6.0
-nltk==3.2.1
+nltk==3.4.5
 numpy
 scipy
 scikit_image