diff --git a/tryton/gui/window/view_form/view/form_gtk/progressbar.py b/tryton/gui/window/view_form/view/form_gtk/progressbar.py
index 1734f5f659..79e2b00f03 100644
--- a/tryton/gui/window/view_form/view/form_gtk/progressbar.py
+++ b/tryton/gui/window/view_form/view/form_gtk/progressbar.py
@@ -16,7 +16,7 @@ class ProgressBar(WidgetInterface):
 
     def __init__(self, field_name, model_name, window, attrs=None):
         super(ProgressBar, self).__init__(field_name, model_name, window,
-                parent, attrs=attrs)
+                attrs=attrs)
         self.widget = gtk.ProgressBar()
         orientation = self.orientations.get(attrs.get('orientation',
             'left_to_right'), gtk.PROGRESS_LEFT_TO_RIGHT)