diff --git a/comic/models.py b/comic/models.py
index 7ef8c54..6bd36e6 100644
--- a/comic/models.py
+++ b/comic/models.py
@@ -143,7 +143,7 @@ def process_comic_book(base_dir, comic_path, comic_file_name):
                      last_read_page=0)
     book.save()
     i = 0
-    for f in sorted(cbx.namelist(), key=str.lower):
+    for f in sorted([str(x) for x in cbx.namelist()], key=str.lower):
         ext = f.lower()[-3:]
         if ext in ['jpg', 'jpeg']:
             page = ComicPage(Comic=book,