diff --git a/book/external/Nested-Books b/book/external/Nested-Books
index 21c0a70..a8e57da 160000
--- a/book/external/Nested-Books
+++ b/book/external/Nested-Books
@@ -1 +1 @@
-Subproject commit 21c0a704f4b4a932e204991ddeb051f7487d9ac4
+Subproject commit a8e57da25302d47806ad1fe4288950c438562199