diff --git a/libavformat/avio.c b/libavformat/avio.c
index 5a1bb966be..7627f4a405 100644
--- a/libavformat/avio.c
+++ b/libavformat/avio.c
@@ -147,7 +147,7 @@ offset_t url_filesize(URLContext *h)
     offset_t pos, size;
     
     pos = url_seek(h, 0, SEEK_CUR);
-    size = url_seek(h, 0, SEEK_END);
+    size = url_seek(h, -1, SEEK_END)+1;
     url_seek(h, pos, SEEK_SET);
     return size;
 }