The ongoing revision of the POSIX.13 standard — real-time profiles for portable operating system interfaces — proposes adding new services to the Minimum Real-Time System Profile that are considered useful to the small embedded applications to which this profile is targeted. Concerns have been raised that these services may introduce too much overhead or may be difficult to implement. In this paper we evaluate the implementation of some of these new services in our MaRTE operating system. The implemented services are the monotonic clock, a high resolution sleep operation with specifiable clock, execution-time clock and timers, the sporadic server scheduling policy, and the timed mutex lock operation. We show that the complexity of these implementations is small, and the overheads introduced by the new services are fully acceptable.