diff --git a/src/library/library.cr b/src/library/library.cr
index 93eac0c..2a5de7d 100644
--- a/src/library/library.cr
+++ b/src/library/library.cr
@@ -136,8 +136,12 @@ class Library
       deleted_entry_ids:         [] of String,
     }
 
+    library_paths = (Dir.entries @dir)
+      .select { |fn| !fn.starts_with? "." }
+      .map { |fn| File.join @dir, fn }
     @title_ids.select! do |title_id|
       title = @title_hash[title_id]
+      next false unless library_paths.includes? title.dir
       existence = title.examine examine_context
       unless existence
         examine_context["deleted_title_ids"].concat [title_id] +
@@ -152,9 +156,7 @@ class Library
     end
 
     cache = examine_context["cached_contents_signature"]
-    (Dir.entries @dir)
-      .select { |fn| !fn.starts_with? "." }
-      .map { |fn| File.join @dir, fn }
+    library_paths
       .select { |path| !(remained_title_dirs.includes? path) }
       .select { |path| File.directory? path }
       .map { |path| Title.new path, "", cache }