"Jennifer Aniston U R amazing Thanx 4 donating $500k for our #PuertoRico relief fund," Martin wrote on Twitter Thursday.
"We will never forget. U R saving lives Jenn #Allin4PR," he continued.
"She is concerned that so much is still needed to be done for the victims of these recent hurricanes, especially Puerto Rico where there is still no power to most of the island," a source said of Aniston to E! News. "She hopes this inspires others to give what they can."