diff --git a/youtube_dl/extractor/changba.py b/youtube_dl/extractor/changba.py
index 3b32e5511..37feef085 100644
--- a/youtube_dl/extractor/changba.py
+++ b/youtube_dl/extractor/changba.py
@@ -39,14 +39,14 @@ class ChangbaIE(InfoExtractor):
         isvideo = self._search_regex(r'&isvideo=([0-9])', webpage, 'isvideo')
         title = self._search_regex(r'<div[^>]+class="title"[^>]*>([^<]+)', webpage, 'title')
 
-        ext = ".mp4"
+        ext = "mp4"
         if int(isvideo) == 0:
-            ext = ".mp3"
+            ext = "mp3"
         
         try:
             url = self._search_regex(r'([a-z]+:\/\/[0-9a-z]+\.changba\.com\/[a-z]+\/[a-z]+\/[0-9]+\/[0-9]+\.mp[3-4])', webpage, 'url')
         except:
-            url = "http://lzscuw.changba.com/" + str(id) + ext
+            url = "http://lzscuw.changba.com/" + str(id) + "." + ext
 
         return {
             'url': url,