The U.S. is 1 of only 17 countries in the world that uses state-imposed forced labor, a form of “modern slavery,” according to a new report from an international human rights group.

Walk Free’s Global Slavery Index 2023 placed the U.S. among the small group of nations — which also includes China, North Korea and Russia — over its use of compulsory prison labor.

The report noted the 13th Amendment includes a caveat that allows involuntary servitude to be used as punishment for a crime.

“Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction,” the amendment reads.

As a result, U.S. prisoners are excluded from many labor law protections “given that compulsory prison labour is considered a legal punishment rather than an economic activity,” according to the report.

The U.S. has the 10th highest estimated number of people in modern-day slavery, with about 1.1 million, the report found.

Globally, there were about 3.9 million people who were forced to work by state authorities in 2021. The largest portion — 2.2 million — were engaged in compulsory prison labor, according to the report.

Another 1.1 million were conscripts who were forced to perform nonmilitary work, and about 700,000 more were engaged in forced labor for economic development.