diff --git a/requirements.txt b/requirements.txt
index 922f869..b008f29 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -21,7 +21,7 @@ matplotlib==2.0.0
 mistune==0.7.4
 nbconvert==5.1.1
 nbformat==4.3.0
-nltk==3.2.4
+nltk==3.4.5
 notebook==5.0.0
 numpy==1.12.1
 olefile==0.44