diff --git a/lib/Epub/Epub/BookMetadataCache.cpp b/lib/Epub/Epub/BookMetadataCache.cpp
index 06b4f458..52e48098 100644
--- a/lib/Epub/Epub/BookMetadataCache.cpp
+++ b/lib/Epub/Epub/BookMetadataCache.cpp
@@ -9,7 +9,7 @@
 #include "FsHelpers.h"
 
 namespace {
-constexpr uint8_t BOOK_CACHE_VERSION = 3;
+constexpr uint8_t BOOK_CACHE_VERSION = 4;
 constexpr char bookBinFile[] = "/book.bin";
 constexpr char tmpSpineBinFile[] = "/spine.bin.tmp";
 constexpr char tmpTocBinFile[] = "/toc.bin.tmp";