diff --git a/vcs/Canvas.py b/vcs/Canvas.py
index 399612636..ed5118597 100644
--- a/vcs/Canvas.py
+++ b/vcs/Canvas.py
@@ -4682,6 +4682,7 @@ def ffmpeg(self, movie, files, bitrate=1024, rate=None, options=None):
 
         """
         args = ["ffmpeg", "-y"]
+        test_file = None
 
         if rate is not None:
             args.extend(("-framerate", str(rate)))