Gotta go? Better not forget the combination.

In response to student concerns about security in Matthews Hall in the wake of recent break-ins, combination locks will be installed this week in each of the dorm's common bathrooms.

Harvard Police will also be strictly enforcing the no-trespassing law, locking gates around Matthews at night and going door-to-door asking students to identify suspects from photo arrays.

The combination locks will require students to punch in a code consisting of three numbers.

According to Yard Superintendent Kathleen Bray, the Freshman Dean's Office will help decide this week whether each bathroom will have its own separate combination.

Notices slipped under the doors of Matthews suites will inform students of the combination, said Merle Bicknell of Yard Operations, and the combinations will be changed periodically during the semester.

The impetus for the combination locks came from Matthews residents, Bicknell said, and administrators decided to go ahead with the idea as a pilot project.

"If it works we will take a look at doing this in other dorms," Bicknell said, "but at this point we only have the problem in Matthews."

Harvard Police Chief Francis D. "Bud" Riley said last week that he supports the addition of the locks.

"I think it's necessary right now, since students are asking for it," he said.

In addition to the new locks, Riley said, police are carefully patrolling the building and the surrounding area, and guards are now locking the gates to the Yard from the Square at earlier times.

The gates between Lehman and Straus Halls and across from Holyoke Center will now close at 7:30 p.m. every day.

In vigorously enforcing the no-trespassing law, Riley said, police will now arrest "anyone who doesn't have a legitimate reason for being in the building," rather than issue warnings to those people.

Riley said Matthews residents have been helpful in contacting police after run-ins with intruders, and he asked that they continue to be vigilant.

"Ninety-five percent of the problem is who gets into the building," Riley said.