diff --git a/requirements.txt b/requirements.txt
index 55e92e0..a2d0c02 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 networkx==1.11
-nltk==3.4.5
+nltk==3.6.6
 chardet==2.2.1
 lxml==4.6.3
 cssselect==0.9.1