diff --git a/requirements.txt b/requirements.txt
index 6c90b1e844..dd44698dea 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 SoundFile==0.10.3.post1
 tensorflow_datasets==4.4.0
-nltk==3.6.4
+nltk==3.6.6
 numpy>=1.19.5
 sentencepiece==0.1.96
 tqdm==4.62.1