diff --git a/requirements.txt b/requirements.txt
index 0f227c2..1144d5e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 joblib==0.13.2
-nltk==3.4.3
+nltk==3.6.6
 numpy==1.16.4
 scikit-learn==0.21.2