diff --git a/requirements.txt b/requirements.txt
index 0bf6cbb..fc60a88 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,7 +15,7 @@ Jinja2==2.10.1
 jmespath==0.9.4
 joblib==0.13.2
 MarkupSafe==1.1.1
-nltk==3.4.1
+nltk==3.6.3
 numpy==1.16.3
 opencv-python==4.1.0.25
 Pillow==6.0.0