diff --git a/tryton/common/datetime_.py b/tryton/common/datetime_.py
index a6765c6be7..b1507c4619 100644
--- a/tryton/common/datetime_.py
+++ b/tryton/common/datetime_.py
@@ -106,6 +106,7 @@ class Date(gtk.Entry):
             self.__calendar.select_month(
                 self.__date.month - 1, self.__date.year)
             self.__calendar.select_day(self.__date.day)
+        self.__cal_popup.set_transient_for(self.get_toplevel())
         popup_position(self, self.__cal_popup)
         popup_show(self.__cal_popup)