Tenant Wants Rent Reduction b/c of Leak

With this winter’s crazy weather, just last month, a leak appeared from our patio (which is also the roof of an extension) into our tenant’s apartment. I have been on the scene each time it has leaked (on two separate occasions over the last month), and I have been trying different things to repair, or at least fix the leak until the weather gets warmer. My tenant keeps mentioning a rent reduction or credit for the rooms that have the leak. What should I do?