diff --git a/book/external/Nested-Books b/book/external/Nested-Books
index f6411e2..73643c5 160000
--- a/book/external/Nested-Books
+++ b/book/external/Nested-Books
@@ -1 +1 @@
-Subproject commit f6411e26f52b806ce1d443a9f35839b7f0536329
+Subproject commit 73643c5462b760b83ebdc231a65b984c39122a2f