diff --git a/requirements.txt b/requirements.txt
index 962a50f..26ecc6a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-nltk==3.4.5
+nltk==3.9
 PyQt5==5.13.1
 PyQt5-sip==12.7.0
 six==1.12.0