diff --git a/include/book.h b/include/book.h
index b7935834..434ba745 100644
--- a/include/book.h
+++ b/include/book.h
@@ -69,6 +69,7 @@ class Book
   const uint64_t& getSize() const { return m_size; }
   const std::string& getFavicon() const { return m_favicon; }
   const std::string& getFaviconMimeType() const { return m_faviconMimeType; }
+  const std::string& getDownloadId() const { return m_downloadId; }
 
   void setReadOnly(bool readOnly) { m_readOnly = readOnly; }
   void setId(const std::string& id) { m_id = id; }
@@ -91,9 +92,11 @@ class Book
   void setSize(uint64_t size) { m_size = size; }
   void setFavicon(const std::string& favicon) { m_favicon = favicon; }
   void setFaviconMimeType(const std::string& faviconMimeType) { m_faviconMimeType = faviconMimeType; }
+  void setDownloadId(const std::string& downloadId) { m_downloadId = downloadId; }
 
  protected:
   std::string m_id;
+  std::string m_downloadId;
   std::string m_path;
   bool m_pathValid;
   std::string m_indexPath;
diff --git a/src/book.cpp b/src/book.cpp
index eb0798b8..52e2d50c 100644
--- a/src/book.cpp
+++ b/src/book.cpp
@@ -123,6 +123,9 @@ void Book::updateFromXml(const pugi::xml_node& node, const std::string& baseDir)
   m_size = strtoull(ATTR("size"), 0, 0);
   m_favicon = base64_decode(ATTR("favicon"));
   m_faviconMimeType = ATTR("faviconMimeType");
+  try {
+    m_downloadId = ATTR("downloadId");
+  } catch(...) {}
 }
 #undef ATTR
 
diff --git a/src/library.cpp b/src/library.cpp
index fea5d83b..28abb90b 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -155,6 +155,10 @@ bool Library::writeToFile(const std::string& path) {
       if (!book.getSize()) {
         bookNode.append_attribute("size") = to_string(book.getSize()).c_str();
       }
+
+      if (!book.getDownloadId().empty()) {
+        bookNode.append_attribute("downloadId") = book.getDownloadId().c_str();
+      }
     }
   }