diff --git a/experiments/requirements.txt b/experiments/requirements.txt
index 1285d64c..7056d6ab 100644
--- a/experiments/requirements.txt
+++ b/experiments/requirements.txt
@@ -13,7 +13,7 @@ idna==3.7
 jsonlines==1.2.0
 Markdown==3.0.1
 mypy==0.670
-nltk==3.6.6
+nltk==3.9
 numpy==1.22.0
 pandas==0.24.1
 protobuf==3.18.3