diff --git a/external/book b/external/book
index cdb5d19301ad7757272342933430dfbaaf6acec7..cb610ecf09bc8505678369c6edd4ec95680517ee 160000
--- a/external/book
+++ b/external/book
@@ -1 +1 @@
-Subproject commit cdb5d19301ad7757272342933430dfbaaf6acec7
+Subproject commit cb610ecf09bc8505678369c6edd4ec95680517ee