diff --git a/book/external/Nested-Books b/book/external/Nested-Books
index 8af34ee..d987234 160000
--- a/book/external/Nested-Books
+++ b/book/external/Nested-Books
@@ -1 +1 @@
-Subproject commit 8af34ee7b400a850c7539252fc4a257291de33d2
+Subproject commit d987234cd93496ce63df5153b114f79c777817b8