diff --git a/src/calibre/ebooks/oeb/reader.py b/src/calibre/ebooks/oeb/reader.py
index 0f61969373..8e11ac6498 100644
--- a/src/calibre/ebooks/oeb/reader.py
+++ b/src/calibre/ebooks/oeb/reader.py
@@ -544,7 +544,7 @@ class OEBReader(object):
             data = render_html_svg_workaround(path, self.logger)
             if not data:
                 data = ''
-        id, href = self.oeb.manifest.generate('cover', 'cover.jpeg')
+        id, href = self.oeb.manifest.generate('cover', 'cover.jpg')
         item = self.oeb.manifest.add(id, href, JPEG_MIME, data=data)
         return item