diff --git a/src/calibre/__init__.py b/src/calibre/__init__.py
index f25a6341ca..9408f7266a 100644
--- a/src/calibre/__init__.py
+++ b/src/calibre/__init__.py
@@ -520,6 +520,7 @@ def get_download_filename(url, cookie_file=None):
         br.set_cookiejar(cj)
 
     with closing(br.open(url)) as r:
+        filename = ''
         disposition = r.info().get('Content-disposition', '')
         for p in disposition.split(';'):
             if 'filename' in p: