Any suggestions on this would be great?

your in a circular room with 2 identical doors and 2 identical sentries guarding each door, one door leads to heaven and the other door leads to hell. The sentry guarding the door to heaven will always tell the truth whereas the sentry guarding the door to hell will always tell lies! you can only ask one question to one of the sentries to find out where the doors lead but cant ask outright if their door leads to heaven. what question do you ask?