diff --git a/diffoscope/progress.py b/diffoscope/progress.py
index 20ae769..f60c404 100644
--- a/diffoscope/progress.py
+++ b/diffoscope/progress.py
@@ -188,7 +188,7 @@ class ProgressBar(object):
 
         self.msg = ""
 
-        class Message(progressbar.Widget):
+        class Message(progressbar.widgets.WidgetBase):
             def update(self, pbar, _observer=self):
                 msg = _observer.msg
                 width = 25