diff --git a/src/library/title.cr b/src/library/title.cr
index 001e9af..88c165b 100644
--- a/src/library/title.cr
+++ b/src/library/title.cr
@@ -36,7 +36,7 @@ class Title
         @title_ids << title.id
         next
       end
-      if [".zip", ".cbz", ".rar", ".cbr"].includes? File.extname path
+      if [".zip", ".cbz", ".rar", ".cbr"].includes? (File.extname path).downcase
         entry = Entry.new path, self
         @entries << entry if entry.pages > 0 || entry.err_msg
       end