North Koreans cannot name their children Jong Un, and those who already share the name of the country's leader must change it. That's according to a directive from 2011 obtained recently by KBS, South Korea's state-run broadcast network.

It's unclear how many people the ban affects, but Kim is a common Korean last name, and both males and females can be named Jong Un. The North Korean directive was dated January 2011, the KBS report said.

Similar directives prevented North Koreans from naming their children after Kim Jong Il, Kim Jong Un's father, and Kim Il Sung, the North Korean leader's grandfather.

Kim Jong Un took over after his father's death in December 2011. Kim Jong Il had ruled since 1994 after his father's death. Their line has ruled North Korea since the country was established in 1948.

The name bans are an attempt to build cults of personality around the Kim dynasty. Their birthdays are important national holidays and North Koreans are required to hang their portraits on their walls.

The New York Times adds:

"South Korean officials have long suspected that a new naming convention was in force once Mr. Kim was publicly introduced as the expected heir to his father in 2010, given the family's history of hoarding names. But as with so much in North Korea, with its tight control on information, it was difficult to confirm."Copyright 2016 NPR. To see more, visit