diff --git a/books/zero_to_deep_learning/requirements.txt b/books/zero_to_deep_learning/requirements.txt
old mode 100755
new mode 100644
index b5ad23a..5972053
--- a/books/zero_to_deep_learning/requirements.txt
+++ b/books/zero_to_deep_learning/requirements.txt
@@ -35,7 +35,7 @@ lxml==4.2.3
 Markdown==2.6.11
 MarkupSafe==1.0
 matplotlib==2.2.2
-mistune==0.8.3
+mistune==2.0.3
 more-itertools==4.2.0
 nbconvert==5.3.1
 nbformat==4.4.0