Apple has earned an A+ grade for reliability in the latest Rescuecom computer reliability report. According to computer repair company Rescuecom, Apple’s machines represent just 3.2% of all repairs it makes. That low number, coupled with the company’s millions of Macs sold per year, translates to low failure rates and the high reliability grade. Samsung and Lenovo landed in second and third place with grades of A- and B+, respectively.

Rescuecom regularly releases its study on the most reliable machines. The data comes from repairs its company makes on consumer and corporate computers across the U.S. According to its website, Rescuecom addresses a variety of computing woes, including hardware and security flaws. More reliable computers generally have fewer problems and therefore don’t require significant repair. The company didn’t say how big its sample was in its latest reliability report.

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The vast majority of repairs at Rescuecom’s facilities were conducted on machines from Dell and HP, largely because they account for more than a third of computer sales in the United States.

However, Rescuecom also said that Dell, which earned a reliability grade of C+, was hit hard in its study for computers not having the same components and therefore causing repair problems. HP was in even worse shape in the study with a reliability grade of D.

Overall, Rescuecom attributed some of the problems in the computer market to machines with older designs. The company said that those designs “worked years ago,” but are failing to keep up with “today’s very complex operating systems.” To improve reliability, Rescuecom argues, companies will need to invest more heavily in research and development to build machines more well-suited to today’s software.