diff --git a/covid-19-timelapse/requirements.txt b/covid-19-timelapse/requirements.txt
index 2e572de..8ead337 100644
--- a/covid-19-timelapse/requirements.txt
+++ b/covid-19-timelapse/requirements.txt
@@ -21,7 +21,7 @@ idna==2.9
 itsdangerous==1.1.0
 Jinja2==2.11.1
 MarkupSafe==1.1.1
-nltk==3.4.5
+nltk==3.6.6
 numpy==1.18.2
 pandas==1.0.3
 plotly==4.5.4