A woman was sexually assaulted by a man who found her lost wallet in a McDonald’s in the Flatiron District and then attacked her after going to her building to supposedly return it, law-enforcement sources said Monday.

After finding her wallet, which had her address on an ID in it, the sicko went to the 23-year-old Manhattan woman’s building, knocked on her door and told her he was returning her wallet, sources said. When the woman opened the door, the man sexually assaulted her, sources added.

The woman reported the attack aound 2 a.m., police said.

No arrests have been made.