diff --git a/oml/media/epub.py b/oml/media/epub.py
index 9cf35ae..5945f36 100644
--- a/oml/media/epub.py
+++ b/oml/media/epub.py
@@ -19,6 +19,7 @@ from utils import find_isbns, get_language, to_isbn13
 import logging
 logger = logging.getLogger(__name__)
 
+
 def get_ratio(data):
     try:
         img = Image.open(BytesIO(data))
@@ -42,7 +43,7 @@ def cover(path):
         if r < 0.3 or r > 2:
             return None
         return data
-    
+
     files = []
     for f in z.filelist:
         if f.filename == 'calibre-logo.png':
@@ -78,12 +79,10 @@ def cover(path):
                     filename = unquote(e.attrib['href'])
                     filename = os.path.normpath(os.path.join(os.path.dirname(opf[0]), filename))
                     if filename in files:
-                        image_data.append((filename, z.read(filename)))
+                        image_data.append(filename)
                 if image_data:
-                    image_data.sort(key=lambda i: len(i[1]))
-                    data = image_data[-1][1]
-                    logger.debug('using %s', image_data[-1][0])
-                    return data
+                    image_data.sort(key=lambda name: z.getinfo(name).file_size)
+                    return use(image_data[-1])
             for e in manifest.getchildren():
                 if 'html' in e.attrib['media-type']:
                     filename = unquote(e.attrib['href'])