diff --git a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
index 67314b91..e01396d7 100644
--- a/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
+++ b/lib/Epub/Epub/parsers/ChapterHtmlSlimParser.cpp
@@ -520,6 +520,7 @@ void XMLCALL ChapterHtmlSlimParser::startElement(void* userData, const XML_Char*
                 // Create page for image - only break if image won't fit remaining space
                 if (self->currentPage && !self->currentPage->elements.empty() &&
                     (self->currentPageNextY + displayHeight > self->viewportHeight)) {
+                  self->paragraphIndexPerPage.push_back(self->xpathParagraphIndex);
                   self->completePageFn(std::move(self->currentPage));
                   self->completedPageCount++;
                   self->currentPage.reset(new Page());
diff --git a/lib/KOReaderSync/ChapterXPathForwardMapper.cpp b/lib/KOReaderSync/ChapterXPathForwardMapper.cpp
index 59477a0b..d6120166 100644
--- a/lib/KOReaderSync/ChapterXPathForwardMapper.cpp
+++ b/lib/KOReaderSync/ChapterXPathForwardMapper.cpp
@@ -99,6 +99,13 @@ std::string makeSpineCacheKey(const std::shared_ptr<Epub>& epub, const int spine
 
 size_t getTotalTextBytesCached(const std::shared_ptr<Epub>& epub, const int spineIndex, const std::string& tmpPath) {
   static std::unordered_map<std::string, size_t> sTotalBytesBySpine;
+  static std::string sCachedBookPath;
+
+  const std::string currentBookPath = epub ? epub->getCachePath() : std::string();
+  if (currentBookPath != sCachedBookPath) {
+    sTotalBytesBySpine.clear();
+    sCachedBookPath = currentBookPath;
+  }
 
   const std::string key = makeSpineCacheKey(epub, spineIndex);
   if (!key.empty()) {
diff --git a/lib/KOReaderSync/ChapterXPathIndexerInternal.cpp b/lib/KOReaderSync/ChapterXPathIndexerInternal.cpp
index a81fd71e..920d30b7 100644
--- a/lib/KOReaderSync/ChapterXPathIndexerInternal.cpp
+++ b/lib/KOReaderSync/ChapterXPathIndexerInternal.cpp
@@ -3,6 +3,7 @@
 #include <HalStorage.h>
 #include <Logging.h>
 
+#include <algorithm>
 #include <cctype>
 #include <unordered_map>
 #include <vector>
@@ -10,9 +11,8 @@
 namespace ChapterXPathIndexerInternal {
 
 std::string toLowerStr(std::string value) {
-  for (char& c : value) {
-    c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
-  }
+  std::transform(value.begin(), value.end(), value.begin(),
+                 [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
   return value;
 }
 
@@ -186,7 +186,7 @@ std::string decompressToTempFile(const std::shared_ptr<Epub>& epub, const int sp
     return "";
   }
 
-  const std::string tmpPath = epub->getCachePath() + "/.tmp_kox.html";
+  const std::string tmpPath = epub->getCachePath() + "/.tmp_kox_" + std::to_string(spineIndex) + ".html";
   if (Storage.exists(tmpPath.c_str())) {
     Storage.remove(tmpPath.c_str());
   }
diff --git a/lib/KOReaderSync/ChapterXPathIndexerState.h b/lib/KOReaderSync/ChapterXPathIndexerState.h
index f0c3b419..fddbea12 100644
--- a/lib/KOReaderSync/ChapterXPathIndexerState.h
+++ b/lib/KOReaderSync/ChapterXPathIndexerState.h
@@ -15,6 +15,7 @@ namespace ChapterXPathIndexerInternal {
 struct StackNode {
   std::string tag;
   int index = 1;
+  // Reserved for future text-node heuristics; intentionally unused for now.
   bool hasText = false;
 };