diff --git a/requirements.txt b/requirements.txt
index ee46b4c..51bc1c1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,7 +9,7 @@ jupyter-core==4.3.0
 matplotlib==2.0.2
 nbconvert==5.2.1
 nbformat==4.3.0
-nltk==3.3
+nltk==3.4.5
 notebook==5.0.0
 numpy==1.15.1
 pandas==0.20.1