Recreational cannabis use may now be legal in Canada, but South Koreans visiting the country who are tempted to smoke up risk facing punishment back home, their government warned on Tuesday.

“Even if South Koreans are in a region where marijuana is legal, it will be illegal for them to consume it,” the South Korean Embassy in Canada said on Twitter. “Please take care not to commit an illegal act and be punished.”

South Koreans have known for decades that they can be prosecuted at home for using drugs overseas, even in countries where consumption is legal.

Under the country’s narcotics law, growing, possessing, transporting or consuming marijuana is a crime punishable by up to five years in prison or a fine of up to 50 million won, about $44,000.

South Koreans are subject to their country’s criminal code no matter where they are in the world.

Prosecutors frequently indict returning citizens who experiment with cannabis, as well as those who frequent casinos while overseas. Gambling, like pot-smoking, is illegal in South Korea.

The authorities typically do not randomly test citizens returning home, but they keep a close watch on those people who have been caught with marijuana in the past. They also occasionally catch people who boast on the internet about using marijuana.

Pop singers and television celebrities caught smoking marijuana are often paraded before the news media, and can be banned from performing as an additional punishment.

Last week Canada became the second country to legalize recreational marijuana, after Uruguay.

There are about 23,000 South Korean students in Canada, according to government data. As of May, 293,000 South Koreans were traveling there.

South Korea has been a vigorous enforcer of anti-drug regulations. Police reported 8,887 cases of narcotics crimes last year, up from 5,699 in 2014. Officers booked 1,044 people on marijuana-related charges last year, a 49 percent increase from 2014.

Marijuana smoking arrived in South Korea with U.S. troops who first came here to fight during the Korean War, and with South Korean soldiers returning from the Vietnam War, historians say. Cannabis was officially banned by Park Chung-hee, a military dictator, in the 1970s.