diff --git a/requirements.txt b/requirements.txt
index 12cc2e08..0ec90822 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-nltk==3.9
+nltk==3.9.3
 tqdm>=4.9.0
 nose>=1.1.2
 numpy>=1.7