Systems and methods for preventing leakage of electromagnetic waves from electronic devices, or for preventing unwanted RF fields from entering an electronic device. According to an aspect, a system includes a body and a cover positioned to define an enclosed interior space for placement of an electronic device. The system also includes a gasket attached to or integrated one of the body and cover to seal the interior space from outside the electronic device enclosure. Further, the system includes an electromagnetic wave absorptive material attached to a portion of the gasket for absorbing electromagnetic waves generated within or outside of the electronic device enclosure.