diff --git a/book/external/Nested-Books b/book/external/Nested-Books
index 3cf6152..63b9a9e 160000
--- a/book/external/Nested-Books
+++ b/book/external/Nested-Books
@@ -1 +1 @@
-Subproject commit 3cf61525f3985916805a59361935764d78e460df
+Subproject commit 63b9a9e747e3fb7511e7e98514648f5d8ee9d010