diff --git a/src/library/entry.cr b/src/library/entry.cr
index 28b7122..bb0aa1b 100644
--- a/src/library/entry.cr
+++ b/src/library/entry.cr
@@ -1,6 +1,8 @@
 require "image_size"
 
 class Entry
+  include YAML::Serializable
+
   getter zip_path : String, book : Title, title : String,
     size : String, pages : Int32, id : String, encoded_path : String,
     encoded_title : String, mtime : Time, err_msg : String?
diff --git a/src/library/library.cr b/src/library/library.cr
index 32cc161..9c23d68 100644
--- a/src/library/library.cr
+++ b/src/library/library.cr
@@ -1,4 +1,6 @@
 class Library
+  include YAML::Serializable
+
   getter dir : String, title_ids : Array(String),
     title_hash : Hash(String, Title)
 
diff --git a/src/library/title.cr b/src/library/title.cr
index f1915d4..899e21f 100644
--- a/src/library/title.cr
+++ b/src/library/title.cr
@@ -2,6 +2,8 @@ require "digest"
 require "../archive"
 
 class Title
+  include YAML::Serializable
+
   getter dir : String, parent_id : String, title_ids : Array(String),
     entries : Array(Entry), title : String, id : String,
     encoded_title : String, mtime : Time, signature : UInt64,