The NYPD is warning its officers that under a new law, they could be arrested in New Jersey if they travel through that state off-duty with high-capacity firearm magazines.

The internal Police Department memo, issued this week, advises New York City cops that if they pass through the neighboring state with a magazine capable of holding more than 10 rounds when they’re not on the clock, they’d be violating the new law.

A federal appeals court earlier this month upheld the law, which limits the magazine size allowed for most gun owners traveling through the Garden State.

While on-duty officers are allowed to carry the large-capacity magazines “while on duty or travelling to or from an authorized place of duty,” the same allowance does not extend to off-duty law enforcement personnel, the memo says.

Legislation is pending to amend the statute and allow for officers to carry large-capacity magazines in all instances, according to the document.