diff --git a/Chapter-4/activity_1/requirements.txt b/Chapter-4/activity_1/requirements.txt
index 424e5fb..77b7450 100644
--- a/Chapter-4/activity_1/requirements.txt
+++ b/Chapter-4/activity_1/requirements.txt
@@ -37,7 +37,7 @@ lxml==4.1.1
 Markdown==2.6.10
 MarkupSafe==1.0
 matplotlib==2.1.0
-mistune==0.8.3
+mistune==2.0.3
 nbconvert==5.3.1
 nbformat==4.4.0
 nose==1.3.7