diff --git a/requirements.txt b/requirements.txt
index f8e14c7..e1d52a8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,7 +28,7 @@ PDPbox @ git+https://github.com/SauceCat/PDPbox.git@73c69665f1663b53984e187c7bc8
 pycebox==0.0.1
 alepython @ git+https://github.com/MaximeJumelle/ALEPython.git@286350ab674980a32270db2a0b5ccca1380312a7
 tensorflow-docs @ git+https://github.com/tensorflow/docs@2d270bdf7da20b5ccd08e15812e57a174522b3cf
-nltk==3.2.5
+nltk==3.4.5
 witwidget==1.7.0
 opencv-python==4.1.2.30
 scikit-image==0.16.2