diff --git a/BDiSN_06_A_Intro/code/requirements.txt b/BDiSN_06_A_Intro/code/requirements.txt
index f68694f..e8b3415 100644
--- a/BDiSN_06_A_Intro/code/requirements.txt
+++ b/BDiSN_06_A_Intro/code/requirements.txt
@@ -22,7 +22,7 @@ matplotlib==2.1.1
 mistune==0.8.3
 nbconvert==5.3.1
 nbformat==4.4.0
-nltk==3.2.5
+nltk==3.6.3
 notebook==5.2.2
 numpy==1.14.0
 oauthlib==2.0.6