diff --git a/github_issue_summarization/requirements.txt b/github_issue_summarization/requirements.txt
index 3857b5c90..fad3c7add 100644
--- a/github_issue_summarization/requirements.txt
+++ b/github_issue_summarization/requirements.txt
@@ -110,7 +110,7 @@ navigator-updater==0.1.0
 nbconvert==5.3.1
 nbformat==4.4.0
 networkx==2.0
-nltk==3.4.5
+nltk==3.9
 nose==1.3.7
 notebook==5.0.0
 numba==0.35.0+10.g143f70e90